Claims

1 . Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

subdivide the picture into transform bocks (84) of different sizes,

select, for a predetermined transform block, a selected transformation (1 12) by

checking whether a size of the predetermined transform block exceeds a predetermined threshold size (1 1 1 )

if the size of the predetermined transform block exceeds the predetermined threshold size (1 1 1 ), using a default way (1 14) for selecting the selected transformation (1 12),

if the size of the predetermined transform block does not exceed the predetermined threshold size (1 1 1 ), using a transformation which is pointed to out of a predetermined list 1 16 of transformations by an index transmitted in the data stream (14) for the predetermined transform block as the selected transformation (1 12), the predetermined list (1 16) of transformations comprising an identity transformation (1 17) and non-identity transformations (1 18),

decode (120), for the predetermined transform block, a block of coefficients from the data stream (14),

if the selected transformation is the identity transformation, use the block of coefficients as residual sample array (132) for the predetermined transform block, and

if the selected transformation is not the identity transformation, subject the block of coefficients to an inverse transformation (131 ) corresponding to the selected transformation to obtain the residual sample array (132) for the predetermined transform block,

correct a prediction (84’c) for the predetermined transform block using the residual sample array (132) to reconstruct the predetermined transform block.

2. Apparatus 100 of claim 1 , configured to,

if the size of the predetermined transform block exceeds the predetermined threshold size, use a default non-identity transformation for the selected transformation.

3. Apparatus 100 of claim 1 or 2, wherein

the default non-identity transformation is contained in the predetermined list of transformations.

4. Apparatus 100 of any one of claims 1 to 3, configured to

derive the predetermined threshold size from the data stream.

5. Apparatus 100 of any one of claims 1 to 4, configured to

decode the index from a current position in the data stream for the predetermined transform block if the size of the predetermined transform block does not exceed the predetermined threshold size, and

decode from the current position of the data stream a syntax element other than the index, if the size of the predetermined transform block exceeds the predetermined threshold size.

6. Apparatus 100 of any one of claims 1 to 5, configured to

decode the index from the data stream for a coding block of the picture which is partitioned into a plurality of transform bocks including the predetermined transform block.

7. Apparatus 100 of any one of claims 1 to 6, wherein the transform blocks are luma transform blocks and the apparatus is configured to use a fixed default transformation for chroma transform blocks.

8. Apparatus 100 of any one of claims 1 to 7, configured to apply the selected transformation to luma and chroma components of the picture within the predetermined transform block.

9. Apparatus 100 of any one of claims 1 to 8, configured to decode the index from the data stream for the predetermined transform block per component of luma and chroma components of the picture.

10. Apparatus 100 of any one of claims 1 to 9, configured to derive from a signal in the data stream whether

the transform blocks are luma transform blocks and a fixed default transformation is to be used for chroma transform blocks,

the selected transformation is to be applied to luma and chroma components of the picture within the predetermined transform block, or

the index from the data stream is to be decoded for the predetermined transform block per component of luma and chroma components of the picture.

1 1. Apparatus 100 of any one of claims 1 to 10, configured

in decoding, for the predetermined transform block, a block of coefficients from the data stream

depending on whether the selected transformation for the predetermined block is contained in a predefined set of one or more transformations,

decode a coded block flag from the data stream signaling whether the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is contained in the predefined set of one or more transformations, and

infer that the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is not contained in the predefined set of one or more transformations.

12. Apparatus 100 according to claim 1 1 , wherein

the predefined set of one or more transformations comprises the identity transformation and a default non-identity transformation selected, by default, according to the default way for selecting the selected transformation.

13. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) by

decoding an index from the data stream for the predetermined transform block, and

using as the selected transformation, one transformation out of a predetermined list of transformations onto which the index points,

decode (120), for the predetermined transform block, a block of coefficients from the data stream,

derive from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block,

wherein the apparatus is configured to, in decoding, for the predetermined transform block, the block of coefficients from the data stream

depending on whether the selected transformation (1 12) for the predetermined block is contained in a predefined set (125, 1 16) of one or more transformations, decode (126) a coded block flag from the data stream (14) signaling whether the block of coefficients (122) has at least one non-zero coefficient (127), if the selected transformation (1 12) for the predetermined block is contained in the predefined set (125, 1 16) of one or more transformations, and

infer that the block of coefficients has at least one non-zero coefficient (127’), if the selected transformation for the predetermined block is not contained in the predefined set of one or more transformations .

14. Apparatus 100 according to claim 1 1 or 13, wherein

the predefined set of one or more transformations comprises the identity transformation.

15. Apparatus 100 of any one of claims 1 to 12, and 13 to 14, configured to

populate, or populate and sort, the predetermined list of transformations depending on the data stream, and

decode the index from the data stream using a variable length code, so that each transformation in the predetermined list of transformations has assigned one codeword of the variable length code and a code word length of the codewords of the variable length code monotonically increases with a rank of the transformation in the predetermined list of transformations to which the codewords are assigned.

16. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream, including decoding (120’) a coded block flag (126’) from the data stream (14) signaling whether the block of coefficients (122) has at least one non-zero coefficient,

wherein the apparatus is configured to, if the coded block flag (126’) signals that the block of coefficients has at least one non-zero coefficient (127i),

select, for a predetermined transform block, a selected transformation (1 12) by decoding (1 15) an index from the data stream for the predetermined transform block, and use as the selected transformation, one transformation out of a predetermined list (1 16, 125) of transformations onto which the index points,

derive (130) from the block of coefficients (122) a residual sample array (132) for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block, and

if the coded block flag signals that the block of coefficients does not have at least one non-zero coefficient (1272),

reconstruct (150) the predetermined transform block without prediction correction.

17. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Populate (160), or populate and sort (160’), a predetermined list (1 16, 125) of transformations depending on the data stream (14), and

select, for a predetermined transform block, a selected transformation (1 12) by

decoding (1 15) an index from the data stream (14) using a variable length code (1 15’), so that each transformation in the predetermined list of transformations has assigned one codeword of the variable length code and a code word length of the codewords of the variable length code monotonically increases with a rank of the transformation in the predetermined list of transformations to which the codewords are assigned, and

using as the selected transformation (1 12), one transformation out of a predetermined list (1 16, 125) of transformations onto which the index points,

decode (120), for the predetermined transform block, a block of coefficients from the data stream,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

18. Apparatus 100 of any one of claims 15 and 17, configured to

sort the predetermined list of transformations depending on a syntax element in the data stream, which is at least valid for the picture globally.

19. Apparatus 100 of any one of claims 15, and 17 to 18, configured to

sort the predetermined list of transformations depending on an evaluation of sample statistics in a spatial neighborhood of the predetermined transform block.

20. Apparatus 100 of any one of claims 15, and 17 to 19, configured to

sort the predetermined list of transformations depending on syntax elements signaled in the data stream for blocks in a spatial neighbourhood of the predetermined transform block.

21 . Apparatus 100 of any one of claims 15, and 17 to 20, configured to

sort the predetermined list of transformations so that there exist at least one state of the data stream so that the sorting the predetermined list of transformations arranged the identity transformation at a leading rank having a shortest codeword of the variable length code assigned thereto.

22. Apparatus 100 of any one of claims 15, and 17 to 21 , configured to

decode an index from the data stream using a composed variable length code codewords of which are composed of a first codeword of a variable length code followed by, if the first codeword is a longest codeword of the variable length code, a second codeword of a fixed length code, and wherein

the codewords of the composed variable length code merely composed of one of two non-longest codewords of the variable length code are assigned to, and discriminate, the identity transformation and a predefined non-identity transformation and

further codewords of the composed variable length code are assigned to, and discriminate, further non-identity transformations of the predetermined list of transformations.

23. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) by

decoding (1 15) an index into a predetermined list (1 16, 125) of transformations from the data stream (14) using a composed variable length code (1 15’) codewords (1 15’a) of which are composed of a first codeword (1 15’ai) of a variable length code followed by, if the first codeword is a longest codeword of the variable length code, a second codeword (1 15’a2) of a fixed length code, wherein

the codewords (1 15’a) of the composed variable length code (1 15’) merely composed of one of two non-longest codewords of the variable length code are assigned to, and discriminate, an identity transformation (1 17) and a predefined non-identity transformation (1 18) contained in the predetermined list of transformations and

further codewords of the composed variable length code are assigned to, and discriminate, further non-identity transformations of the predetermined list of transformations,

using as the selected transformation, one transformation out of a predetermined list of transformations onto which the index points,

decode (120), for the predetermined transform block, a block of coefficients from the data stream,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

24. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation (1 12) comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients from the data stream (14) by

checking (123) whether the selected transform is a non-identity transformation,

if the selected transform is a non-identity transformation,

decoding (125) a position information (121 ai) from the data stream on where along a scanning order (85) which traverses all coefficients of the block of coefficients, a non-zero coefficient (121 a) is encountered first or where along a scanning order which traverses all coefficients of the block of coefficients, a non-zero coefficient is encountered last, so as to obtain predetermined coefficient position (121 ai), and

decoding first coefficients (121 a) of the block of coefficients from the data stream, which include all non-zero coefficients of the block of coefficients and are traversed by the scanning order (85) starting from or up to the predetermined coefficient position (121 ai), and inferring second coefficients (121 b) of the block of coefficients (122), different from the first coefficients (121 a), to be zero,

if the selected transform is the identity transformation,

decoding (121’) all coefficients of the block of coefficients from the data stream,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

25. Apparatus 100 of claim 24, configured to

in the decoding of the first coefficients of the block of coefficients from the data stream, use the scanning order and

start the decoding of the first coefficients at the predetermined coefficient position, so that the first coefficient are traversed by the scanning order starting from the predetermined coefficient position, or

finish the decoding of the first coefficients at the predetermined coefficient position, so that the first coefficient are traversed by the scanning order up to the predetermined coefficient position,

in the decoding of all coefficients of the block of coefficients from the data stream, sequentially decode all coefficients starting or finishing at a coefficient of the block of coefficients which is traversed last by the scanning order.

26. Apparatus 100 of claim 24 or 25, configured to

in the decoding of all coefficients of the block of coefficients from the data stream, use the scanning order and finish the decoding of all coefficients at a coefficient of the block of coefficients traversed last by the scanning order or use the inverse scanning order and start the decoding of all coefficients at the coefficient of the block of coefficients traversed last by the scanning order.

27. Apparatus 100 of any one of claims 24 to 26, configured to

decode the position information by

decoding coordinates of the predetermined coefficient position from the data steam, or

decoding a rank of the predetermined coefficient position within the scanning order from the data stream.

28. Apparatus 100 of any one of claims 24 to 27, configured to

Perform the decoding of the first coefficients of the block of coefficients, in sub-blocks into which the block of coefficients is partitioned, so that the scanning order traverses all first coefficients within one sub-block before traversing first coefficients within a different sub block and by inferring first coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, to be zero, and decoding first coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness from the data stream, with

decoding the sub-block flags from the data stream except at least one of a first sub-block flag relating to a sub-block comprising the predetermined coefficient position, and a second sub-block flag relating to a sub-block comprising a first coefficient of the block of coefficients between which and the predetermined coefficient position the first coefficients are located, and inferring the at least one of the first and second sub-block flags to signal non-zeroness, and

perform the decoding of all coefficients of the block of coefficients from the data stream in the sub-blocks into which the block of coefficients is partitioned, so that the scanning order traverses all coefficients within one sub-block before traversing first coefficients within a different sub-block and by inferring coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, to be zero, and decoding coefficients within sub blocks for which a sub-block flag in the data stream signals non-zeroness from the data stream, with

decoding the sub-block flags from the data stream for all sub-blocks.

29. Apparatus 100 of claim 28, configured to,

in the decoding of the sub-block flags from the data stream for all sub-blocks,

decode the sub-block flags from the data stream for all sub-blocks sequentially in a sub-block order, and

infer the sub-block flag being last in sub-block order to signal non-zeroness, if all preceding sub-block flags preceding in sub-block order signal zeroness.

30. Apparatus 100 of claim 29, configured to,

in the decoding of the sub-block flags from the data stream for all sub-blocks,

decode the sub-block flags from the data stream for all sub-blocks sequentially in a sub-block order, and

if all preceding sub-block flags preceding in sub-block order signal zeroness, decode the coefficients within a predetermined sub-block for which sub-block flag being last in sub-block order is inferred to signal non-zeroness sequentially in coefficient order and decode for each coefficient within the predetermined sub-block, except a last coefficient, a significance flag indicating whether the respective coefficient is non-zero, and infer the last coefficient to be non-zero if the other coefficients within the predetermined sub-block are zero, and decode a significance flag for the last coefficient if at least one of the other coefficients within the predetermined sub-block is non-zero,

in the decoding of the sub-block flags from the data stream except the at least one of the first sub-block flag and the second sub-block flag,

decode the sub-block flags from the data stream except the at least one of the first sub-block flag and the second sub-block flag, and infer same to signal non zeroness, and

inevitably decode for all first coefficients within the sub-block to which the second sub-block flag relates, a significance flag indicating whether the respective coefficient is non-zero.

31 . Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream (14) by

decoding the coefficients of the block of coefficients from the data stream in sub blocks (122i to 1224) into which the block of coefficients (122) is partitioned, by inferring coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, to be zero, and decoding coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness from the data stream, with

if the selected transformation is one of the at least one non-identity transformation (123i), sequentially decoding (200i) the sub-block flags from the data stream (14) except at least one of a first sub-block flag (210i), and a last sub-block flag (210n), and inferring the at least one of the first and last sub-block flags to signal non zeroness, and

if the selected transformation is the identity transformation (1232), decoding (2002) the sub-block flags from the data stream for all sub-blocks,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

32. Apparatus 100 of any one of claims 28 and 31 , configured to, in the decoding of the sub-block flags from the data stream for all sub-blocks,

decode the sub-block flags from the data stream for all sub-blocks sequentially in a sub-block order, and

decode a sub-block flag being last in the sub-block order if at least one of preceding sub-block flags preceding in sub-block order, signals non-zeroness, and infer the sub-block flag being last in sub-block order to signal non-zeroness if all preceding sub block flags preceding in sub-block order, signal zeroness.

33. Apparatus 100 of claim 32, configured to

when inferring the sub-block flag being last in sub-block order to signal non zeroness, infer a last coefficient within the sub-block for which the last sub-block flag is inferred to signal non-zeroness to indicate non-zeroness if all preceding coefficients within said sub-block are zero.

34. Apparatus 100 of any one of claims 28, and 31 to 33, configured to decode a currently decoded sub-block flag from the data stream by context adaptive entropy decoding and using

a context which depends on

a logical disjunction of sub-block flags relating to sub-blocks neighboring the currently decoded sub-block flag if the selected transformation is one of the at least one non-identity transformation, and

a arithmetic sum of sub-block flags relating to sub-blocks neighboring the currently decoded sub-block flag if the selected transformation is the identity transformation.

35. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients from the data stream by

Decoding (121 ) the coefficients of the block of coefficients from the data stream in sub-blocks into which the block of coefficients is partitioned, by inferring coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, to be zero, and decoding coefficients within sub-blocks for which a sub block flag in the data stream signals non-zeroness from the data stream, with decoding a currently decoded sub-block flag from the data stream by context adaptive entropy decoding and using a context (300) which depends on

a logical disjunction (310) of sub-block flags relating to sub-blocks neighboring the currently decoded sub-block flag if the selected transformation is one of the at least one non-identity transformation, and

a arithmetic sum (320) of sub-block flags relating to sub-blocks neighboring the currently decoded sub-block flag if the selected transformation is the identity transformation,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

36. Apparatus 100 of any one of claims 28, 31 to 34, and 35, configured to decode for a current coefficient within a sub-block for which a sub-block flag in the data stream signals non-zeroness from the data stream a significance flag indicative of whether the current coefficient is zero or not using a context which depends on

a number of coefficients being non-zero among a first set of coefficients immediately neighboring the current coefficient if the selected transformation is the identity transformation, and

a number of coefficients being non-zero among a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the current coefficient than the first set of coefficients, values of the second set of coefficients and a position of the current coefficient if the selected transformation is one of the at least one non-identity transformation.

37. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding (400) for a current coefficient a significance flag indicative of whether the current coefficient is zero or not using a context (300) which depends on

a number of coefficients (310) being non-zero among a first set of coefficients immediately neighboring the current coefficient if the selected transformation is the identity transformation, and

a number of coefficients (320) being non-zero among a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the current coefficient than the first set of coefficients, values of the second set of coefficients and a position of the current coefficient if the selected transformation is one of the at least one non-identity transformation,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

38. Apparatus 100 of any one of claims 28, 31 to 34, 35 to 36, and 37, configured to decode a predetermined coefficient by

context adaptively entropy decoding N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

decoding, using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, with

N being larger if the selected transformation is the identity transformation, than compared to if the selected transformation is one of the at least one non-identity transformation.

39. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding a predetermined coefficient by

context adaptively entropy decoding (500) N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

decoding (600), using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, with

N being larger if the selected transformation is the identity transformation, than compared to if the selected transformation is one of the at least one non-identity transformation,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

40. Apparatus 100 of any one of claims 38 and 39, configured to perform the context adaptively entropy decoding of the N greater-than-X flags in a sequence of passes by context adaptively entropy decoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass, wherein the apparatus is configured to log a number of flags coded using context adaptively entropy decoding during the sequence of passes and to cease the context adaptively entropy decoding of the N greater-than-X flags if the number exceeds a predetermined flag threshold.

41. Apparatus 100 of any one of claims 38, and 39 to 40, wherein the variable length code is a Rice code, and the apparatus is configured to determine a Rice parameter of the Rice code depending on

a first set of coefficients immediately neighboring the predetermined coefficient if the selected transformation is the identity transformation, and

a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the predetermined coefficient than the first set of coefficients if the selected transformation is one of the at least one non identity transformation.

42. Apparatus 100 of any one of claims 38, and 39 to 41 , configured to decode a sign of the predetermined coefficient by

context adaptive entropy decoding using a predetermined context and updating a probability associated with the predetermined context if the selected transformation is the identity transformation, and

bypass encoding if the selected transformation is one of the at least one non identity transformation.

43. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 10) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding (700) a sign of a predetermined coefficient by

context adaptive entropy decoding using a predetermined context (710) and updating a probability associated with the predetermined context if the selected transformation is the identity transformation, and

bypass decoding if the selected transformation is one of the at least one non identity transformation,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

44. Apparatus 100 of claim 43, configured to

select the predetermined context among a plurality of context depending on a statistic of signs of previously decoded coefficients if the selected transformation is the identity transformation.

45. Apparatus 100 of claim 44, configured to

select the predetermined context depending on a relative frequency of positive or negative signs among non-zero coefficients within the previously decoded coefficients if the selected transformation is the identity transformation.

46. Apparatus 100 of any one of claims 43 to 45, configured to

set the number context models of the plurality of context models to a default number; and/or

derive the number context models of the plurality of context models from the data stream; and/or

associate the context models with mutually adjoining and non-overlapping relative frequency intervals for a relative frequency of positive or negative signs and perform the selection so that among the relative frequency of positive or negative signs among non zero coefficients of the previously decoded coefficients falls into the relative frequency interval associated with the predetermined context model; and/or

determine the statistic over the signs of the previously decoded coefficients so that the previously decoded coefficients are spread over a picture or video portion larger than the predetermined transform block; and/or

entropy decode the signs of all non-zero coefficients of the predetermined transform block using the predetermined context model if the selected transformation is the identity transformation; and/or

entropy decode the signs of a subset of non-zero coefficients of the predetermined transform block located in a sub-block of the block of coefficients and including the non zero predetermined coefficient using the predetermined context model, and update the statistic using the signs of a subset of non-zero coefficients of the predetermined

transform block to obtain an updated statistic, select a further predetermined context model among the plurality of context models depending on the updated statistic and entropy decode the signs of a further subset of non-zero coefficients of the predetermined transform block located in a further sub-block of the block of coefficients using the further predetermined context model if the selected transformation is the identity transformation; and/or

update a sign probability associated with the predetermined context model based on the sign of the predetermined non-zero coefficient if the selected transformation is the identity transformation; and/or

wherein the plurality of context models is sub-divided into sets of context models and the apparatus is configured to

perform the selection by

selecting a predetermined set of contexts models based on the statistic of signs of previously decoded coefficients, and

selecting the predetermined predetermined context model among the selected set of context models depending on the sign of one or more neighboring non-zero coefficients if the selected transformation is the identity transformation.

47. Apparatus 100 of any one of claims 38, and 39 to 42, and 43 to 46, configured to

if the selected transformation is one of the at least one non-identity transformation, perform the context adaptively entropy decoding of the N greater-than-X flags in a sequence of passes by context adaptively entropy decoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass, and log a number of flags coded using context adaptively entropy decoding during the sequence of passes and to cease the context adaptively entropy decoding of the N greater-than-X flags if the number exceeds a predetermined flag threshold, and

if the selected transformation is the identity transformation, perform the context adaptively entropy decoding of the N greater-than-X flags sequentially and decode, after decoding a significance flag (X=0) among the N greater-than-X flags and prior to further N greater-than-X flags among the N greater-than-X flags, a greater-than-X-flags-bypass flag indicative of whether the predetermined coefficient is greater than the absolute threshold and cease the context adaptively entropy decoding of the N greater-than-X flags with respect to the further greater-than-X flags in case of the greater-than-X-flags-bypass flag indicating that the predetermined coefficient is greater than the absolute threshold.

48. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding a predetermined coefficient by

context adaptively entropy decoding (800) N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

decoding (810), using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N,

wherein the apparatus is configured to

if the selected transformation is one of the at least one non-identity transformation, perform the context adaptively entropy decoding (800) of the N greater-than-X flags in a sequence (830) of passes by context adaptively entropy decoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass (820i to 82O3), and log a number of flags coded using context adaptively entropy

decoding during the sequence of passes and to cease the context adaptively entropy decoding of the N greater-than-X flags if the number (832) exceeds a predetermined flag threshold (834), and

if the selected transformation is the identity transformation, perform the context adaptively entropy decoding of the N greater-than-X flags sequentially and decode, after decoding a significance flag (840) among the N greater-than-X flags and prior to further N greater-than-X flags among the N greater-than-X flags, a greater-than-X-flags-bypass flag (850) indicative of whether the predetermined coefficient is greater than the absolute threshold and cease the context adaptively entropy decoding of the N greater-than-X flags with respect to the further greater-than-X flags in case of the greater-than-X-flags-bypass flag indicating that the predetermined coefficient is greater than the absolute threshold (852),

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

49. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream, in a sequence of passes (820i to 82O3) which traverse the coefficients of the block of coefficients in a predetermined scan order (85), by, for a predetermined coefficient,

context adaptively entropy decoding (800) N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

decoding (810), using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, and

decoding a sign of the predetermined coefficient,

wherein the apparatus is configured to differently distribute the decoding of the N greater-than-X flags, the remainder and the sign over the sequence of passes depending on the selected transformation being the identity transformation or being one of the at least one non-identity transformation,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

50. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream (14) by

decoding, in a sequence of passes (820i to 82O3) which traverse the coefficients of the block,

one or more predetermined flags (92, 96, 98, 104) for each coefficient from the data stream using context adaptively binary entropy decoding, each predetermined flag reducing an absolute value domain (90) of the

respective coefficient within which an absolute value of the respective coefficient is positioned, and

for each coefficient for which a cardinality of the absolute value domain (90) is not reduced down to one by the one or more predetermined flags (92, 96, 98, 104) decoded for the respective coefficient, a variable length code codeword (8705) indicating the absolute value of the respective coefficient within the absolute value domain of the respective coefficient,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block,

wherein the apparatus is configured to,

in decoding, in the sequence of passes, the one or more predetermined flags, cease the decoding the one or more predetermined flags as soon as a predetermined number of predetermined flags has been reached so that the cardinality of the absolute value domain within which the pointer points to the absolute value is smaller for a first set of non-zero coefficients compared a second set of non-zero coefficients, and

use different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients.

51. Apparatus 100 of claim 50, wherein the different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients differ in a binarization boundary between a transitioning from a unary part to a Rice- and Exp-Golomb part and/or a binarization parameter of common binarization scheme.

52. Apparatus 100 of claim 50, wherein the different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients differ in a different dependency of a binarization boundary between a transitioning from a unary part to a Rice- and Exp-Golomb part and/or a binarization parameter of common binarization scheme on previous decoded coefficients.

53. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by

if the selected transform is a non-identity transformation (123i),

decoding the coefficients of the block of coefficients from the data stream along a first scan order (85i) leading towards a DC coefficient of the non identity transformation, and

if the selected transform is the identity transformation (1232),

decoding the coefficients of the block of coefficients from the data stream along a second scan order (852) leading from an upper left sample position to a lower right sample position,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

54. Apparatus 100 of claim 53, configured to select the second scan order depending on DPCM direction using which the predetermined transform block is coded.

55. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream (14) by

if the selected transformation is one of the at least one non-identity transformation (123i), decoding (900) a syntax element from the data stream (14), deriving therefrom whether signs of non-zero coefficients within a predetermined group of non-zero coefficients are equal to each other (910) or not (920) and, if so (910), the signs of the non-zero coefficients within the predetermined group of non-zero coefficients (930) and, if the signs of the non-zero coefficients within the predetermined group of non-zero coefficients are not equal to each other (920), decoding (940) the signs of the non-zero coefficients within the predetermined group of non-zero coefficients by decoding sign bits on a per non-zero-coefficient basis, and

if the selected transformation is the identity transformation (1232), decoding (940) the signs of the non-zero coefficients within the predetermined group of non-zero coefficients by decoding sign bits on a per non-zero-coefficient basis irrespective of the signs of the non-zero coefficients within the predetermined group of non zero coefficients being equal to each other or not, and

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

56. Apparatus 100 of claim 55, configured to determine the predetermined group of non-zero coefficients as those non-zero coefficients within the block of coefficients which are located within a predetermined sub-block of the block of coefficients.

57. Apparatus 100 of claim 56, configured to

if the selected transformation is one of the at least one non-identity transformation, decode a further syntax element from the data stream, derive therefrom whether signs of non-zero coefficients within a further predetermined group of non-zero coefficients are equal to each other or not and, if so, the signs of the non-zero coefficients within the further predetermined group of non-zero coefficients and, if the signs of the non-zero coefficients within the further predetermined group of non-zero coefficients are not equal to each other, decoding the signs of the non zero coefficients within the further predetermined group of non-zero coefficients by decoding further sign bits on a per non-zero-coefficient basis, and

group non-zero coefficients of the block of coefficients into a plurality of groups of non-zero coefficients including the group of non-zero coefficients and the further group of non-zero coefficients.

58. Apparatus 100 of claim 59, configured to perform the grouping based on

a subdivision of the block of coefficients into sub-blocks so that each group of non zero coefficients comprises only non-zero coefficients located in one of the sub blocks.

59. Apparatus 100 of claim 58, configured to adapt the subdivision

With respect to a size of a predetermined sub-block based on signs of one or more non-zero coefficients in one or more of the sub-blocks preceding the predetermined sub-block in a sub-block decoding order, and/or

based on signs of previously decoded non-zero coefficients.

60. Apparatus 100 of claim 55, configured to determine the predetermined group of non-zero coefficients so as to include all non-zero coefficients within the block of coefficients.

61. Apparatus 100 of any one of claims 55 to 59, configured to

if the selected transformation is one of the at least one non-identity transformation, decoding a block-global syntax element from the data stream, deriving therefrom whether signs of all non-zero coefficients within the predetermined transform block are equal to each other or not and, if so, the signs of all non-zero coefficients within the predetermined transform block and, if not the signs of all non-zero coefficients within the predetermined transform block are equal to each other, performing the decoding the syntax element from the data stream.

62. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding signs of non-zero coefficients of the predetermined block of coefficients by

deriving (1 100) a sign probability tendency index (1 1 10) from the data stream (14) and entropy decoding (1000) the sign of a predetermined non-zero coefficient using a context model associated with the sign probability tendency index (1 1 10) if the selected transformation is the identity transformation (1232), and

bypass decoding (1200) the sign of the predetermined non-zero coefficient if the selected transformation is one of the at least one non-identity transformation (123!),

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

63. Apparatus 100 of claim 62, configured to

entropy decode the signs of all non-zero coefficients using the context model associated with the sign probability tendency index if the selected transformation is the identity transformation, and

bypass decoding the signs of all predetermined non-zero coefficients if the selected transformation is one of the at least one non-identity transformation.

64. Apparatus 100 of claim 62 or 63, configured to

update a sign probability associated with the context model associated with the sign probability tendency index based on the sign of the predetermined non-zero coefficient if the selected transformation is the identity transformation.

65. Apparatus 100 of claim 62, wherein a number of context models are associated with the sign probability tendency index and the apparatus is configured to

entropy decode each of the signs of non-zero coefficients using a predetermined context model among the number of context models associated with the sign probability tendency index and select the predetermined context model among the number of context models associated with the sign probability tendency index depending on the sign of one or more neighboring non-zero coefficients if the selected transformation is the identity transformation, and

bypass decode the signs of all predetermined non-zero coefficients if the selected transformation is one of the at least one non-identity transformation.

66. Apparatus 100 of claim 65, configured to

select the predetermined context model among the number of context models associated with the sign probability tendency index depending on a frequency of a positive or negative sign among the one or more neighboring non-zero coefficients if the selected transformation is the identity transformation.

67. Apparatus 100 of any one of claims 62 to 66, wherein

the sign probability tendency index is signaled in the data stream specifically for a sub-block of the coefficient block within which the predetermined non-zero coefficient is located, the predetermined transform block, a coding block containing the predetermined transform block, a picture slice containing the predetermined transform block the picture or a picture sequence containing the picture.

68. Apparatus 100 of any one of claims 62 to 67, configured to

Read, from the data stream, an information on which of different sets of context models with different cardinalities applies to the sign probability tendency index, wherein the sign probabilities associated with the context models are distributed more dense within a first set of context models than within a second set of context models having a cardinality lower than the cardinality of the first set of context models,

Select the context model by using the sign probability tendency index as a pointer into the set of context models applying to the sign probability tendency index.

69. Apparatus 100 of any one of claims 62 to 68, wherein

the sign probability tendency index is signaled in the data stream specifically for a picture slice containing the predetermined transform block, the picture or a picture sequence containing the picture.

70. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by decoding signs of non-zero coefficients of the predetermined block of coefficients by

decoding (1000i) the sign of a predetermined non-zero coefficient using a predetermined context model (1300) among a plurality of context models and select (1310) the predetermined context model (1300) among the plurality of context models depending on a statistic (1400) of signs of previously decoded coefficients if the selected transformation is the identity transformation (1232), and

bypass decoding (10002) the sign of the predetermined non-zero coefficient if the selected transformation is one of the at least one non-identity transformation (123i),

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block.

71 . Apparatus 100 of claim 70 , configured to

select the predetermined context model depending on a relative frequency of positive or negative signs among non-zero coefficients within the previously decoded coefficients if the selected transformation is the identity transformation.

72. Apparatus 100 of claim 70 and 71 , configured to

Set the number context models of the plurality of context models to a default number.

73. Apparatus 100 of claim 70 or 71 , configured to

Derive the number context models of the plurality of context models from the data stream.

74. Apparatus 100 of any one of claims 70 to 73, configured to

Associate the context models with mutually adjoining and non-overlapping relative frequency intervals for a relative frequency of positive or negative signs and perform the selection so that among the relative frequency of positive or negative signs among non zero coefficients of the previously decoded coefficients falls into the relative frequency interval associated with the predetermined context model.

75. Apparatus 100 of any one of claims 70 to 74, configured to determine the statistic over the signs of the previously decoded coefficients so that the previously decoded coefficients are spread over a picture or video portion larger than the predetermined transform block.

76. Apparatus 100 of any one of claims 70 to 75, configured to

entropy decode the signs of all non-zero coefficients of the predetermined transform block using the predetermined context model if the selected transformation is the identity transformation.

77. Apparatus 100 of any one of claims 70 to 76, configured to

entropy decode the signs of a subset of non-zero coefficients of the predetermined transform block located in a sub-block of the block of coefficients and including the non-zero predetermined coefficient using the predetermined context model, and update the statistic using the signs of a subset of non-zero coefficients of the predetermined transform block to obtain an updated statistic, select a further predetermined context model among the plurality of context models depending on the updated statistic and entropy decode the signs of a further subset of non-zero coefficients of the predetermined transform block located in a further sub-block of the block of coefficients using the further predetermined context model if the selected transformation is the identity transformation.

78. Apparatus 100 of any one of claims 70 to 77, configured to

update a sign probability associated with the predetermined context model based on the sign of the predetermined non-zero coefficient if the selected transformation is the identity transformation.

79. Apparatus 100 of any one of claims 70 to 78, wherein the plurality of context models is sub-divided into sets of context models and the apparatus is configured to

perform the selection by

selecting a predetermined set of contexts models based on the statistic of signs of previously decoded coefficients, and

selecting the predetermined predetermined context model among the selected set of context models depending on the sign of one or more neighboring non-zero coefficients if the selected transformation is the identity transformation.

80. Apparatus 100 for decoding a picture using predictive coding and block-based transform residual coding, configured to

Select (1 10), for a predetermined transform block, a selected transformation (1 12) out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

Decode (120), for the predetermined transform block, a block of coefficients (122) from the data stream by

decoding, in a sequence of passes which traverse the coefficients of the block,

one or more predetermined flags (92, 96, 98, 104) for each coefficient from the data stream (14) using context adaptively binary entropy decoding, each predetermined flag reducing an absolute value domain (90) of the respective coefficient within which an absolute value of the respective coefficient is positioned, and

for each coefficient for which a cardinality of the absolute value domain (90) is not reduced down to one by the one or more predetermined flags decoded for the respective coefficient, a variable length code codeword for identifying the absolute value of the respective coefficient out of the absolute value domain of the respective coefficient,

derive (130) from the block of coefficients a residual sample array for the predetermined transform block so that the block of coefficients is related to the residual sample array according to the selected transformation,

correct (140) a prediction for the predetermined transform block using the residual sample array to reconstruct the predetermined transform block,

wherein the apparatus is configured to, in decoding, in the sequence of passes (820i to 8203), the one or more predetermined flags (92, 96, 98, 104), cease the decoding the one or more predetermined flags as soon as a predetermined number (834) of predetermined flags has been reached so that the cardinality of the absolute value domain (90) is smaller for a first set of non-zero coefficients compared a second set of non-zero coefficients, except with respect to a significance flag (92, 840) among the one or more predetermined flags, which indicates whether the coefficient for which it is decoded is zero or not, wherein the predetermined number (834) corresponds to an upper limit minus a number of coefficients for which the significance flag (92, 840) has not yet been decoded.

81. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

subdivide the picture into transform bocks of different sizes,

select, for a predetermined transform block, a selected transformation by

checking whether a size of the predetermined transform block exceeds a predetermined threshold size

if the size of the predetermined transform block exceeds the predetermined threshold size, using a default way for selecting the selected transformation,

if the size of the predetermined transform block does not exceed the predetermined threshold size, choosing a transformation out of a predetermined list of transformations and transmit in the data stream an index which points to the chosen transform out of the predetermined list of transformations so as to be used for the predetermined transform block as the selected transformation, the predetermined list of transformations comprising an identity transformation and non-identity transformations,

predict the predetermined transform block and encode, for the predetermined transform block, a block of coefficients into the data stream, so that

if the selected transformation is the identity transformation, the block of coefficients is to be used as residual sample array for correcting the prediction to reconstruct the predetermined transform block, and

if the selected transformation is not the identity transformation, the block of coefficients is to be subject to an inverse transformation corresponding to the selected transformation to obtain the residual sample array for the predetermined transform block.

82. Apparatus of claim 81 , configured to,

if the size of the predetermined transform block exceeds the predetermined threshold size, use a default non-identity transformation for the selected transformation.

83. Apparatus of claim 81 or 82, wherein

the default non-identity transformation is contained in the predetermined list of transformations.

84. Apparatus of any one of claims 81 to 83, configured to

derive the predetermined threshold size from the data stream.

85. Apparatus of any one of claims 81 to 84, configured to

encode the index into a current position in the data stream for the predetermined transform block if the size of the predetermined transform block does not exceed the predetermined threshold size, and

encode into the current position of the data stream a syntax element other than the index, if the size of the predetermined transform block exceeds the predetermined threshold size.

86. Apparatus of any one of claims 81 to 85, configured to

encode the index into the data stream for a coding block of the picture which is partitioned into a plurality of transform bocks including the predetermined transform block.

87. Apparatus of any one of claims 81 to 86, wherein the transform blocks are luma transform blocks and the apparatus is configured to use a fixed default transformation for chroma transform blocks.

88. Apparatus of any one of claims 81 to 87, configured to apply the selected transformation to luma and chroma components of the picture within the predetermined transform block.

89. Apparatus of any one of claims 81 to 888, configured to encode the index into the data stream for the predetermined transform block per component of luma and chroma components of the picture.

90. Apparatus of any one of claims 81 to 89, configured to signal in the data stream whether

the transform blocks are luma transform blocks and a fixed default transformation is to be used for chroma transform blocks,

the selected transformation is to be applied to luma and chroma components of the picture within the predetermined transform block, or

the index from the data stream is to be encoded for the predetermined transform block per component of luma and chroma components of the picture.

91. Apparatus of any one of claims 81 to 90, configured

in encoding, for the predetermined transform block, a block of coefficients into the data stream

depending on whether the selected transformation for the predetermined block is contained in a predefined set of one or more transformations,

encode a coded block flag into the data stream signaling whether the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is contained in the predefined set of one or more transformations, and

infer that the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is not contained in the predefined set of one or more transformations.

92. Apparatus according to claim 91 , wherein

the predefined set of one or more transformations comprises the identity transformation and a default non-identity transformation selected, by default, according to the default way for selecting the selected transformation.

93. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations onto and encoding an index into the data stream for the predetermined transform block, which points in the predetermined list of transformations onto the selected transformation,

predict the predetermined transform block and encode, for the predetermined transform block, a block of coefficients into the data stream, so that

from the block of coefficients a residual sample array for the predetermined transform block is derivable so that the block of coefficients is related to the residual sample array according to the selected transformation, and

the prediction for the predetermined transform block is correctable using the residual sample array to reconstruct the predetermined transform block,

wherein the apparatus is configured to, in encoding, for the predetermined transform block, the block of coefficients into the data stream

depending on whether the selected transformation for the predetermined block is contained in a predefined set of one or more transformations,

encode a coded block flag into the data stream signaling whether the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is contained in the predefined set of one or more transformations, and

refrain from encoding the coded block flag into the data stream with the coded block flag having to be inferred at encoder side as signaling that the block of coefficients has at least one non-zero coefficient, if the selected transformation for the predetermined block is not contained in the predefined set of one or more transformations.

94. Apparatus according to claim 91 or 93, wherein

the predefined set of one or more transformations comprises the identity transformation.

95. Apparatus of any one of claims 81 to 92, and 93 to 94, configured to

populate, or populate and sort, the predetermined list of transformations depending on the data stream, and

encode the index into the data stream using a variable length code, so that each transformation in the predetermined list of transformations has assigned one codeword of the variable length code and a code word length of the codewords of the variable length code monotonically increases with a rank of the transformation in the predetermined list of transformations to which the codewords are assigned.

96. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

predict a predetermined transform block and encode, for the predetermined transform block, a block of coefficients into the data stream, including encoding a coded block flag into the data stream signaling whether the block of coefficients has at least one non-zero coefficient,

wherein the apparatus is configured to, if the coded block flag signals that the block of coefficients has at least one non-zero coefficient,

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations and encoding an index into the data stream for the predetermined transform block which points in the predetermined list of transformations onto the selected transformation,

wherein from the block of coefficients a residual sample array for the predetermined transform block is derivable so that the block of coefficients is related to the residual sample array according to the selected transformation, and so that the prediction for the predetermined transform block is correctable using the residual sample array to reconstruct the predetermined transform block, and

if the coded block flag signals that the block of coefficients does not have at least one non-zero coefficient,

the predetermined transform block is to be reconstructed without prediction correction.

97. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

populate, or populate and sort, a predetermined list of transformations depending on the data stream, and

select, for a predetermined transform block, a selected transformation out of the predetermined list of transformations and

encoding an index into the data stream which points onto the selected transformation in the predetermined list of transformations using a variable length code, so that each transformation in the predetermined list of transformations has assigned one codeword of the variable length code and a code word length of the codewords of the variable length code monotonically increases with a rank of the transformation in the predetermined list of transformations to which the codewords are assigned, and

derive a prediction for the predetermined transform block and encode, for the predetermined transform block, a block of coefficients into the data stream, so that

from the block of coefficients a residual sample array for the predetermined transform block is derivable so that the block of coefficients is related to the residual sample array according to the selected transformation, and so that the predetermined transform block is recontructible by prediction for the predetermined transform block is correctable using the residual sample array to reconstruct the predetermined transform block.

98. Apparatus of any one of claims 95 and 97, configured to

sort the predetermined list of transformations depending on a syntax element in the data stream, which is at least valid for the picture globally.

99. Apparatus of any one of claims 95, and 97 to 98, configured to

sort the predetermined list of transformations depending on an evaluation of sample statistics in a spatial neighborhood of the predetermined transform block.

100. Apparatus of any one of claims 95, and 97 to 99, configured to

sort the predetermined list of transformations depending on syntax elements signaled in the data stream for blocks in a spatial neighbourhood of the predetermined transform block.

101 . Apparatus of any one of claims 95, and 97 to 100, configured to

sort the predetermined list of transformations so that there exist at least one state of the data stream so that the sorting the predetermined list of transformations arranged the identity transformation at a leading rank having a shortest codeword of the variable length code assigned thereto.

102. Apparatus of any one of claims 95, and 97 to 101 , configured to

encode an index into the data stream using a composed variable length code codewords of which are composed of a first codeword of a variable length code followed by, if the first codeword is a longest codeword of the variable length code, a second codeword of a fixed length code, and wherein

the codewords of the composed variable length code merely composed of one of two non-longest codewords of the variable length code are assigned to, and discriminate, the identity transformation and a predefined non-identity transformation and

further codewords of the composed variable length code are assigned to, and discriminate, further non-identity transformations of the predetermined list of transformations.

103. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

derive a prediction for a predetermined transform block,

select, for a predetermined transform block, a selected transformation from into a predetermined list of transformations and

encoding an index into a predetermined list of transformations into the data stream which points onto the selected transformation using a composed variable length code codewords of which are composed of a first codeword of a variable length

code followed by, if the first codeword is a longest codeword of the variable length code, a second codeword of a fixed length code, wherein

the codewords of the composed variable length code merely composed of one of two non-longest codewords of the variable length code are assigned to, and discriminate, an identity transformation and a predefined non identity transformation contained in the predetermined list of transformations and

further codewords of the composed variable length code are assigned to, and discriminate, further non-identity transformations of the predetermined list of transformations,

encode, for the predetermined transform block, a block of coefficients into the data stream, so that

the block of coefficients is related to the residual sample array according to the selected transformation, and so that

the predetermined transform block is reconstructible by correcting the prediction of the predetermined transform block using the residual sample array.

104. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block and encode, for the predetermined transform block, a block of coefficients into the data stream by

checking whether the selected transform is a non-identity transformation,

if the selected transform is a non-identity transformation,

encoding a position information into the data stream on where along a scanning order which traverses all coefficients of the block of coefficients, a non-zero coefficient is encountered first or where along a scanning order which traverses all coefficients of the block of coefficients, a non-zero coefficient is encountered last, so as to obtain predetermined coefficient position, and

encoding first coefficients of the block of coefficients into the data stream, which include all non-zero coefficients of the block of coefficients and are traversed by the scanning order starting from or up to the predetermined coefficient position, and inferring second coefficients of the block of coefficients, different from the first coefficients, to be zero,

if the selected transform is the identity transformation,

encoding all coefficients of the block of coefficients into the data stream,

wherein the block of coefficients is related to the residual sample array according to the selected transformation and

the predetermined transform block is reconstructible by correcting the prediction thereof using the residual sample array.

105. Apparatus of claim 104, configured to

in the encoding of the first coefficients of the block of coefficients into the data stream, use the scanning order and

start the encoding of the first coefficients at the predetermined coefficient position, so that the first coefficient are traversed by the scanning order starting from the predetermined coefficient position, or

finish the encoding of the first coefficients at the predetermined coefficient position, so that the first coefficient are traversed by the scanning order up to the predetermined coefficient position,

in the encoding of all coefficients of the block of coefficients into the data stream, sequentially encode all coefficients starting or finishing at a coefficient of the block of coefficients which is traversed last by the scanning order.

106. Apparatus of claim 104 or 105, configured to

in the encoding of all coefficients of the block of coefficients into the data stream, use the scanning order and finish the encoding of all coefficients at a coefficient of the block of coefficients traversed last by the scanning order or use the inverse scanning order and start the encoding of all coefficients at the coefficient of the block of coefficients traversed last by the scanning order.

107. Apparatus of any one of claims 104 to 106, configured to

encode the position information by

encoding coordinates of the predetermined coefficient position into the data steam, or

encoding a rank of the predetermined coefficient position within the scanning order into the data stream.

108. Apparatus of any one of claims 104 to 106, configured to

perform the encoding of the first coefficients of the block of coefficients, in sub-blocks into which the block of coefficients is partitioned, so that the scanning order traverses all first coefficients within one sub-block before traversing first coefficients within a different sub block wherein first coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, are inferred to be zero, and first coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness are encoded into the data stream, with

encoding the sub-block flags into the data stream except at least one of a first sub block flag relating to a sub-block comprising the predetermined coefficient position, and a second sub-block flag relating to a sub-block comprising a first coefficient of the block of coefficients between which and the predetermined coefficient position the first coefficients are located, wherein the at least one of the first and second predetermined sub-block flags are to be inferred to signal non-zeroness, and

perform the encoding of all coefficients of the block of coefficients into the data stream in the sub-blocks into which the block of coefficients is partitioned, so that the scanning order traverses all coefficients within one sub-block before traversing first coefficients within a different sub-block wherein coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, are inferred to be zero, and coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness are encoded into the data stream, with

encoding the sub-block flags into the data stream for all sub-blocks.

109. Apparatus of claim 108, configured to,

in the encoding of the sub-block flags into the data stream for all sub-blocks,

encode the sub-block flags into the data stream for all sub-blocks sequentially in a sub-block order, and

not encode the sub-block flag being last in sub-block order with same being to be inferred to signal non-zeroness, if all preceding sub-block flags preceding in sub-block order signal zeroness.

1 10. Apparatus of claim 109, configured to,

in the encoding of the sub-block flags into the data stream for all sub-blocks,

encode the sub-block flags into the data stream for all sub-blocks sequentially in a sub-block order, and

if all preceding sub-block flags preceding in sub-block order signal zeroness, encode the coefficients within a predetermined sub-block for which sub-block flag being last in sub-block order is inferred to signal non-zeroness sequentially in coefficient order and encode for each coefficient within the predetermined sub-block, except a last coefficient, a significance flag indicating whether the respective coefficient is non-zero, and infer the last coefficient to be non-zero if the other coefficients within the predetermined sub-block are zero, and encode a significance flag for the last coefficient if at least one of the other coefficients within the predetermined sub-block is non-zero,

in the encoding of the sub-block flags into the data stream except the at least one of the first sub-block flag and the second sub-block flag,

encode the sub-block flags into the data stream except the at least one of the first sub-block flag and the second sub-block flag, which are to be inferred to signal non-zeroness, and

inevitably encode for all first coefficients within the sub-block to which the second sub-block flag relates, a significance flag indicating whether the respective coefficient is non-zero.

1 1 1. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by

encoding the coefficients of the block of coefficients into the data stream in sub blocks into which the block of coefficients is partitioned, wherein coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, are inferred to be zero, and coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness are encoded into the data stream, with

if the selected transformation is one of the at least one non-identity transformation, sequentially encoding the sub-block flags into the data stream except at least one of a first sub-block flag, and a last sub-block flag, wherein the at least one of the first and last sub-block flags are to be inferred to signal non-zeroness, and

if the selected transformation is the identity transformation, encoding the sub-block flags into the data stream for all sub-blocks,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by correcting the prediction for the predetermined transform block using the residual sample array.

1 12. Apparatus of claim 108 and 1 1 1 , configured to, in the encoding of the sub-block flags into the data stream for all sub-blocks,

encode the sub-block flags into the data stream for all sub-blocks sequentially in a sub-block order, and

encode a sub-block flag being last in the sub-block order if at least one of preceding sub-block flags preceding in sub-block order, signals non-zeroness, wherein the sub-block flag being last in sub-block order is to be inferred to signal non-zeroness if all preceding sub-block flags preceding in sub-block order, signal zeroness.

1 13. Apparatus of claim 1 12, configured to

when inferring the sub-block flag being last in sub-block order to signal non-zeroness, infer a last coefficient within the sub-block for which the last sub-block flag is inferred to signal non-zeroness to indicate non-zeroness if all preceding coefficients within said sub-block are zero.

1 14. Apparatus of claims 108, and 1 1 1 to 1 13, configured to encode a currently encoded sub-block flag into the data stream by context adaptive entropy encoding and using

a context which depends on

a logical disjunction of sub-block flags relating to sub-blocks neighboring the currently encoded sub-block flag if the selected transformation is one of the at least one non-identity transformation, and

a arithmetic sum of sub-block flags relating to sub-blocks neighboring the currently encoded sub-block flag if the selected transformation is the identity transformation.

1 15. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by

encoding the coefficients of the block of coefficients into the data stream in sub blocks into which the block of coefficients is partitioned, by inferring coefficients within sub-blocks for which a sub-block flag in the data stream signals zeroness, to be zero, and encoding coefficients within sub-blocks for which a sub-block flag in the data stream signals non-zeroness into the data stream, with encoding a currently encoded sub-block flag into the data stream by context adaptive entropy encoding and using a context which depends on

a logical disjunction of sub-block flags relating to sub-blocks neighboring the currently encoded sub-block flag if the selected transformation is one of the at least one non-identity transformation, and

a arithmetic sum of sub-block flags relating to sub-blocks neighboring the currently encoded sub-block flag if the selected transformation is the identity transformation,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is recontructible by correcting the prediction for the predetermined transform block using the residual sample array.

1 16. Apparatus of any one of claims 108, 1 1 1 to 1 14, and 1 15, configured to encode for a current coefficient within a sub-block for which a sub-block flag in the data stream signals non-zeroness into the data stream a significance flag indicative of whether the current coefficient is zero or not using a context which depends on

a number of coefficients being non-zero among a first set of coefficients immediately neighboring the current coefficient if the selected transformation is the identity transformation, and

a number of coefficients being non-zero among a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the current coefficient than the first set of coefficients, values of the second set of coefficients and a position of the current coefficient if the selected transformation is one of the at least one non-identity transformation.

1 17. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding for a current coefficient a significance flag indicative of whether the current coefficient is zero or not using a context which depends on

a number of coefficients being non-zero among a first set of coefficients immediately neighboring the current coefficient if the selected transformation is the identity transformation, and

a number of coefficients being non-zero among a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the current coefficient than the first set of coefficients, values of the second set of coefficients and a position of the current coefficient if the selected transformation is one of the at least one non-identity transformation,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by correcting the prediction for the predetermined transform block using the residual sample array.

1 18. Apparatus of any one of claims 108, 1 1 1 to 1 14, 1 15 to 1 16, and 1 17, configured to encode a predetermined coefficient by

context adaptively entropy encoding N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

encoding, using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, with

N being larger if the selected transformation is the identity transformation, than compared to if the selected transformation is one of the at least one non-identity transformation.

1 19. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding a predetermined coefficient by

context adaptively entropy encoding N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

encoding, using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, with

N being larger if the selected transformation is the identity transformation, than compared to if the selected transformation is one of the at least one non-identity transformation,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by correcting the prediction of the predetermined transform block using the residual sample array.

120. Apparatus of any one of claims 1 18 and 1 19, configured to perform the context adaptively entropy encoding of the N greater-than-X flags in a sequence of passes by context adaptively entropy encoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass, wherein the apparatus is configured to log a number of flags coded using context adaptively entropy encoding during the sequence of passes and to cease the context adaptively entropy encoding of the N greater-than-X flags if the number exceeds a predetermined flag threshold.

121. Apparatus of any one of claims 1 18, and 1 19 to 120, wherein the variable length code is a Rice code, and the apparatus is configured to determine a Rice parameter of the Rice code depending on

a first set of coefficients immediately neighboring the predetermined coefficient if the selected transformation is the identity transformation, and

a second set of coefficients which comprises the first set of coefficients and coefficients positioned farther away from the predetermined coefficient than the first set of coefficients if the selected transformation is one of the at least one non identity transformation.

122. Apparatus of any one of claims 1 18, and 1 19 to 121 , configured to encode a sign of the predetermined coefficient by

context adaptive entropy encoding using a predetermined context and updating a probability associated with the predetermined context if the selected transformation is the identity transformation, and

bypass encoding if the selected transformation is one of the at least one non identity transformation.

123. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding a sign of a predetermined coefficient by

context adaptive entropy encoding using a predetermined context and updating a probability associated with the predetermined context if the selected transformation is the identity transformation, and

bypass encoding if the selected transformation is one of the at least one non identity transformation,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by correcting the prediction of the predetermined transform block using the residual sample array.

124. Apparatus of any of previous claims 1 18, and 1 19 to 122, and 123, configured to

if the selected transformation is one of the at least one non-identity transformation, perform the context adaptively entropy encoding of the N greater-than-X flags in a sequence of passes by context adaptively entropy encoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass, and log a number of flags coded using context adaptively entropy encoding during the sequence of passes and to cease the context adaptively entropy encoding the N greater-than-X flags if the number exceeds a predetermined flag threshold, and

if the selected transformation is the identity transformation, perform the context adaptively entropy encoding of the N greater-than-X flags sequentially and encode, after encoding a significance flag (X=0) among the N greater-than-X flags and prior to further N greater-than-X flags among the N greater-than-X flags, a greater-than-X-flags-bypass flag indicative of whether the predetermined coefficient is greater than the absolute threshold and cease the context adaptively entropy encoding of the N greater-than-X flags with respect to the further greater-than-X flags in case of the greater-than-X-flags-bypass flag indicating that the predetermined coefficient is greater than the absolute threshold.

125. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding a predetermined coefficient by

context adaptively entropy encoding N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

encoding, using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N,

wherein the apparatus is configured to

if the selected transformation is one of the at least one non-identity transformation, perform the context adaptively entropy encoding of the N greater-than-X flags in a sequence of passes by context adaptively entropy encoding the N greater-than-X flags sequentially with increasing X with one or more of the N greater-than-X flags per pass, and log a number of flags coded using context adaptively entropy encoding during the sequence of passes and to cease the context adaptively entropy encoding of the N greater-than-X flags if the number exceeds a predetermined flag threshold, and

if the selected transformation is the identity transformation, perform the context adaptively entropy encoding of the N greater-than-X flags sequentially and encode, after encoding a significance flag (X=0) among the N greater-than-X flags and prior to further N greater-than-X flags among the N greater-than-X flags, a greater-than-X-flags-bypass flag indicative of whether the predetermined coefficient is greater than the absolute threshold and cease the context adaptively entropy encoding the N greater- than-X flags with respect to the further greater-than-X flags in case of the greater-than-X-flags-bypass flag indicating that the predetermined coefficient is greater than the absolute threshold,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by correcting the prediction of the predetermined transform block using the residual sample array.

126. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

derive a prediction for the predetermined transform block,

encode, for the predetermined transform block, a block of coefficients into the data stream, in a sequence of passes which traverse the coefficients of the block of coefficients in a predetermined scan order, by, for a predetermined coefficient,

context adaptively entropy encoding N greater-than-X flags indicative of whether an absolute of the predetermined coefficient is greater than X or not,

encoding, using a variable length code, a remainder indicative of an amount at which the absolute of the predetermined coefficient exceeds an absolute threshold which depends on N, and

encoding a sign of the predetermined coefficient,

wherein the apparatus is configured to differently distribute the encoding of the N greater-than-X flags, the remainder and the sign over the sequence of passes depending on the selected transformation being the identity transformation or being one of the at least one non-identity transformation,

wherein the block of coefficients is related to the residual sample array according to the selected transformation, and the predetermined transform block is reconstructible by

correcting the prediction of the predetermined transform block using the residual sample array.

127. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

encode, for the predetermined transform block, a block of coefficients into the data stream by

encoding, in a sequence of passes which traverse the coefficients of the block,

one or more predetermined flags for each coefficient into the data stream using context adaptively binary entropy encoding, each predetermined flag reducing an absolute value domain of the respective coefficient within which an absolute value of the respective coefficient is positioned, and

for each coefficient for which a cardinality of the absolute value domain is not reduced down to one by the one or more predetermined flags encoded for the respective coefficient, a variable length code codeword indicating the absolute value of the respective coefficient within the absolute value domain of the respective coefficient,

so that the block of coefficients is related to a residual sample array for the predetermined transform block according to the selected transformation, the residual sample array allowing for

correcting a prediction for the predetermined transform block to reconstruct the predetermined transform block,

wherein the apparatus is configured to,

in encoding, in the sequence of passes, the one or more predetermined flags, cease the encoding the one or more predetermined flags as soon as a

predetermined number of predetermined flags has been reached so that the cardinality of the absolute value domain within which the pointer points to the absolute value is smaller for a first set of non-zero coefficients compared a second set of non-zero coefficients and

use different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients.

128. Apparatus of claim 127, wherein the different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients differ in a binarization boundary between a transitioning from a unary part to a Rice- and Exp-Golomb part and/or a binarization parameter of common binarization scheme.

129. Apparatus of claim 127, wherein the different variable length codes for the variable length code codeword of the first and second sets of non-zero coefficients differ in a different dependency of a binarization boundary between a transitioning from a unary part to a Rice- and Exp-Golomb part and/or a binarization parameter of common binarization scheme on previous encoded coefficients.

130. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

encode, for the predetermined transform block, a block of coefficients into the data stream by

if the selected transform is a non-identity transformation,

encoding the coefficients of the block of coefficients into the data stream along a first scan order leading towards a DC coefficient of the non-identity transformation, and

if the selected transform is the identity transformation,

encoding the coefficients of the block of coefficients into the data stream along a second scan order leading from an upper left sample position to a lower right sample position,

so that the block of coefficients is related to a residual sample array for the predetermined transform block according to the selected transformation which allows for correcting a prediction for the predetermined transform block to reconstruct the predetermined transform block.

131 . Apparatus of claim 130, configured to select the second scan order depending on DPCM direction using which the predetermined transform block is coded.

132. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

encode, for the predetermined transform block, a block of coefficients into the data stream by

if the selected transformation is one of the at least one non-identity transformation, encoding a syntax element into the data stream, deriving therefrom whether signs of non-zero coefficients within a predetermined group of non-zero coefficients are equal to each other or not and, if so, the signs of the non-zero coefficients within the predetermined group of non-zero coefficients and, if the signs of the non-zero coefficients within the predetermined group of non-zero coefficients are not equal to each other, encoding the signs of the non-zero coefficients within the predetermined group of non-zero coefficients by encoding sign bits on a per non zero-coefficient basis, and

if the selected transformation is the identity transformation, encoding the signs of the non-zero coefficients within the predetermined group of non-zero coefficients by encoding sign bits on a per non-zero-coefficient basis irrespective of the signs of the non-zero coefficients within the predetermined group of non-zero coefficients being equal to each other or not, and

so that the block of coefficients is related to a residual sample array for the predetermined transform block according to the selected transformation, wherein the residual sample array allows to correct a prediction for the predetermined transform block to reconstruct the predetermined transform block.

133. Apparatus of claim 132, configured to determine the predetermined group of non zero coefficients as those non-zero coefficients within the block of coefficients which are located within a predetermined sub-block of the block of coefficients.

134. Apparatus of claim 132, configured to

if the selected transformation is one of the at least one non-identity transformation, encode a further syntax element into the data stream, which signals whether signs of non-zero coefficients within a further predetermined group of non-zero coefficients are equal to each other or not and, if so, the signs of the non-zero coefficients within the further predetermined group of non-zero coefficients and, if the signs of the non-zero coefficients within the further predetermined group of non-zero coefficients are not equal to each other, encode the signs of the non-zero coefficients within the further predetermined group of non-zero coefficients by encoding further sign bits on a per non-zero-coefficient basis, and

group non-zero coefficients of the block of coefficients into a plurality of groups of non-zero coefficients including the group of non-zero coefficients and the further group of non-zero coefficients.

135. Apparatus of claim 134, configured to perform the grouping based on

a subdivision of the block of coefficients into sub-blocks so that each group of non zero coefficients comprises only non-zero coefficients located in one of the sub blocks.

136. Apparatus of claim 135, configured to adapt the subdivision

With respect to a size of a predetermined sub-block based on signs of one or more non-zero coefficients in one or more of the sub-blocks preceding the predetermined sub-block in a sub-block encoding order, and/or

based on signs of previously encoded non-zero coefficients.

137. Apparatus of claim 132, configured to determine the predetermined group of non zero coefficients so as to include all non-zero coefficients within the block of coefficients.

138. Apparatus of any one of claims 132 to 137, configured to

if the selected transformation is one of the at least one non-identity transformation, encoding a block-global syntax element into the data stream, deriving therefrom whether signs of all non-zero coefficients within the predetermined transform block are equal to each other or not and, if so, the signs of all non-zero coefficients within the predetermined transform block and, if not the signs of all non-zero coefficients within the predetermined transform block are equal to each other, performing the encoding the syntax element into the data stream.

139. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding signs of non-zero coefficients of the predetermined block of coefficients by

encoding a sign probability tendency index into the data stream and entropy encoding the sign of a predetermined non-zero coefficient using context model associated with the sign probability tendency index if the selected transformation is the identity transformation, and

bypass encoding the sign of the predetermined non-zero coefficient if the selected transformation is one of the at least one non-identity transformation,

so that the block of coefficients is related to a residual sample array for the predetermined transform block according to the selected transformation, wherein a prediction for the predetermined transform block is correctible using the residual sample array to reconstruct the predetermined transform block.

140. Apparatus of claim 139, configured to

entropy encode the signs of all non-zero coefficients using the context model associated with the sign probability tendency index if the selected transformation is the identity transformation, and

bypass encode the signs of all predetermined non-zero coefficients if the selected transformation is one of the at least one non-identity transformation.

141. Apparatus of claim 139 or 140, configured to

update a sign probability associated with the context model associated with the sign probability tendency index based on the sign of the predetermined non-zero coefficient if the selected transformation is the identity transformation.

142. Apparatus of claim 139, wherein a number of context models are associated with the sign probability tendency index and the apparatus is configured to

entropy encode each of the signs of non-zero coefficients using predetermined context models among the number of context models associated with the sign probability tendency index and select the predetermined context model among the number of context models associated with the sign probability tendency index depending on the sign of one or more neighboring non-zero coefficients if the selected transformation is the identity transformation, and

bypass encode the signs of all predetermined non-zero coefficients if the selected transformation is one of the at least one non-identity transformation.

143. Apparatus of claim 142, configured to

select the predetermined context model among the number of context models associated with the sign probability tendency index depending on a frequency of a positive or negative sign among the one or more neighboring non-zero coefficients if the selected transformation is the identity transformation.

144. Apparatus of any one of claims 139 to 143, wherein

the sign probability tendency index is signaled in the data stream specifically for a sub-block of the coefficient block within which the predetermined non-zero coefficient is located, the predetermined transform block, a coding block containing the predetermined transform block, a picture slice containing the predetermined transform block the picture or a picture sequence containing the picture.

145. Apparatus of any one of claims 139 to 144, configured to

insert, into the data stream, an information on which of different sets of context models with different cardinalities applies to the sign probability tendency index, wherein the sign probabilities associated with the context models are distributed more dense within a first set of context models than within a second set of context models having a cardinality lower than the cardinality of the first set of context models,

wherein the sign probability tendency index selects the context model as a pointer into the set of context models applying to the sign probability tendency index.

146. Apparatus of any one of claims 139 to 145, wherein

the sign probability tendency index is signaled in the data stream specifically for a picture slice containing the predetermined transform block, the picture or a picture sequence containing the picture.

147. Apparatus for encoding a picture using predictive coding and block-based transform residual coding, configured to

select, for a predetermined transform block, a selected transformation out of a predetermined list of transformations, the selected transformation comprising the identity transformation and at least one non-identity transformation,

encode, for the predetermined transform block, a block of coefficients into the data stream by encoding signs of non-zero coefficients of the predetermined block of coefficients by

encoding the sign of a predetermined non-zero coefficient using a predetermined context model among a plurality of context models and select the predetermined context model among the plurality of context models depending on a statistic of signs of previously encoded coefficients if the selected transformation is the identity transformation, and

bypass encoding the sign of the predetermined non-zero coefficient if the selected transformation is one of the at least one non-identity transformation,

so that the block of coefficients is related to a residual sample array for the predetermined transform block according to the selected transformation, so that

a prediction for the predetermined transform block is correctible using the residual sample array to reconstruct the predetermined transform block.

148. Apparatus of claim 147, configured to

select the predetermined context model depending on a relative frequency of positive or negative signs among non-zero coefficients within the previously encoded coefficients if the selected transformation is the identity transformation.

149. Apparatus of claim 148, configured to

Set the number context models of the plurality of context models to a default number.

150. Apparatus of claim 147 or 148, configured to

insert information on the number context models of the plurality of context models in the data stream.