[DESCRIPTION] [Title of Invention] IMAGE DECODING METHOD, AND IMAGE DECODING APPARATUS [Technical Field] [0001] The present invention relates to image decoding methods of decoding multiview video, and image decoding apparatuses which decode multiview video. [Background Art] [0002] Multiview Video Coding (MVC) standard is defined as an extension of ISO/IEC 14496-10 Advanced Video Coding (AVC) standard. The profiles created in the MVC standard are designed to be backward compatible to some of the profiles defined in the AVC standards. In another words, the decoders or players conforming to the new MVC profiles are capable of decoding some of bit streams conforming to the AVC profiles. Vice versa, legacy decoders of the AVC profiles (particularly, the High profile) should also decode at least one of the views in bit streams conforming to the new MVC profiles. [0003] In the Multiview Video Coding (MVC) standard, as a coded base view is required to be compatible with the profiles defined by the AVC standard, a legacy decoder conforming to the High Profile of the AVC standard should be capable of decoding the base view in an MVC bit stream conforming to the MVC profiles. The coded view is contained in Network Abstraction Layer (NAL) units. NAL units of different types are differentiated by NAL unit type values. A non-base view is contained in NAL units having a NAL unit type value reserved in the previous versions of the AVC standard. Thus, the NAL units should be ignored by a legacy high profile decoder. [0004] However, in the MVC standard, a particular NAL unit called a prefix NAL unit is required to be located before each of NAL units for a coded base view and sent together with the NAL unit. This prefix NAL unit has a NAL unit type value of 14 and is reserved in the previous versions of the AVC standard. A NAL unit for a coded base view shall either have a NAL unit type value of 5 or 1, [0005] The prefix NAL unit contains additional parameters that are located in the MVC extension part of a NAL unit header. These parameters are associated with a base view, and are used in the encoding and decoding processes of a corresponding non-base view. Fig. 23 Is a diagram on the location of NAL unit header MVC extension syntaxes. The parameters in the NAL unit header MVC extension part include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), an inter-view prediction flag (inter_view_flag), and a reserved 1-bit (reserved_one_blt). The reserved 1-bit (reserved_one_bit) has a value, and is not used for the encoding and decoding processes of a non-base view. [0006] Patent Literature (PTL) 1 discloses a technique of coding multiview video using NAL units. [Citation List] [Patent Literature] [0007] [PTL 1] International Patent Application Publication No. WO2007/126509 [Summary of Invention] [Technical Problem] [0008] Ideally, legacy AVC decoders should ignore NAL units having NAL unit type values defined as values reserved in the previous versions of the AVC specification. Legacy AVC decoders should decode only the NAL units for base views and reconstruct only the base views, [0009] However, not all decoders in the market will ignore these NAL units having reserved values. A compressed base view and a compressed non-base view can be separated using different stream identifiers. However, as it is required to include prefix NAL units associated with the compressed base view, some decoders in the market cannot decode the base view due to the prefix NAL units. This creates problems in supporting backward compatibility of compressed MVC streams on legacy AVC decoders. [0010] In addition, a prefix NAL unit must be located before each of the NAL units of a base view. Accordingly, it is not easy to add a new view to a bitstream that represents only a single view and does not include prefix NAL units. In other words, it is difficult to modify a bitstream generated based on a conventional standard to a bitstream representing a multlview video. Therefore, it was difficult to utilize a conventional bitstream generated based on such a conventional standard as a view in a multlview video. [0011] Considering this, the present invention has an object to provide image coding methods allowing coding of multlview video and/or image decoding methods allowing decoding of multlview video even when no prefix NAL units are used. [Solution to Problem] [0012] In order to solve the aforementioned problems, an image decoding method according to the present invention is for decoding a multlview video, and includes: parsing NAL units Including an image included in view components of a base view; decoding the image included in the view components of the base view; parsing NAL unit header MVC extension parameters of a non-base view; searching the view components of the base view for prefix NAL units; computing NAL unit header MVC extension parameters for the base view when no prefix NAL units are present in the view components of the base view; parsing, when prefix NAL units are present in the view components of the base view, the NAL unit header MVC extension parameters of the base view, with reference to the prefix NAL units; parsing NAL units including an image included in view components of the non-base view; and decoding the image included in the view components of the non-base view, using (i) the computed or parsed NAL unit header MVC extension parameters of the base view and (ii) the parsed NAL unit header MVC extension parameters of the non-base view. [0013] In this way, a multiview video is decoded even when no prefix NAL units are used. [0014] In addition, each of the base view and the non-base view may be assigned with the NAL unit header MVC extension parameters including a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0015] In this way, a non-base view is decoded using various parameters. [0016] In addition, the computing NAL unit header MVC extension parameters for the base view may include: obtaining a value of the non-IDR flag (non_ idr_flag) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the non-IDR flag (non_idr_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the non-IDR flag (non_idr_flag) included in the NAL unit header MVC extension parameters of the base view; assigning a first predefined value to the priority ID (priority_id) Included in the NAL unit header MVC extension parameters of the base view; assigning a second predefined value to the view ID (viewid) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the temporal ID (temporal_id) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the temporal ID (temporal_id) obtained from among the NAL unit header MVC extension parameters of the non-base view to the temporal ID (temporal_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the anchor picture flag (anchor_pic_flag) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the anchor picture flag (anchor_pic_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the anchor picture flag (anchor_pic_flag) included In the NAL unit header MVC extension parameters of the base view; and assigning a third predefined value to the inter-view prediction flag (inter_view_flag) included in the NAL unit header MVC extension parameters of the base view. [0017] In this way, NAL unit header MVC extension parameters of a base view are specifically computed. [0018] In addition, the computing NAL unit header MVC extension parameters for the base view may include; obtaining a value of a NAL unit type (nal_unit_type) from among NAL unit headers of the base view; assigning 0 to the non-IDR flag (non_idr_flag) Included in the NAL unit header MVC extension parameters of the base view if the value of the NAL unit type (nal_unit_type) is 5; assigning 1 to the non-IDR flag (non_idr_flag) Included in the NAL unit header MVC extension parameters of the base view if the value of the NAL unit type (nal_unit_type) is 1; assigning a first predefined value to the priority ID (priority_id) included in the NAL unit header MVC extension parameters of the base view; assigning a second predefined value to the view ID (view_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the temporal ID (temporal_id) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the temporal ID (tempora_id) obtained from among the NAL unit header MVC extension parameters of the non-base view to the temporal ID (temporal_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the anchor picture flag (anchor_pic_fla9) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the anchor picture flag (anchor_plc_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the anchor picture flag (anchor_pic_flag) Included in the NAL unit header MVC extension parameters of the base view; and assigning a third predefined value to the inter-view prediction flag (lnter_view_flag) Included In the NAL unit header MVC extension parameters of the base view. [0019] In this way, NAL unit header MVC extension parameters for a base view are specifically computed. In addition, the use of the NAL unit headers of a base view makes it possible to compute more precise values. [0020] In addition, the first predefined value assigned to the priority ID (prlorlty_ld) may be 0. [0021] In this way, a base view Is handled preferentially. [0022] In addition, the second predefined value assigned to the view ID (view_id) may be 0. [0023] In this way, the view ID (view_id) of a base view is a distinguishable fixed value. [0024] In addition, the third predefined value assigned to the inter-view prediction flag (inter_view_flag) may be 1. [0025] In this way, a decoded (mage of a base view can be used for inter-view prediction. [0026] In addition, an image coding method is for coding a multiview video, and may include: coding an image of a base view; writing view components including the coded image of the base view into NAL units without using prefix NAL units; determining NAL unit header MVC extension parameters of a non-base view; computing NAL unit header MVC extension parameters for the base view; coding an Image of the non-base view, using the computed NAL unit header MVC extension parameters of the base view and the determined NAL unit header MVC extension parameters of the non-base view; and writing view components including the coded Image of the non-base view into NAL units. [0027] In this way, a multiview video Is coded without using prefix NAL units. [0028] In addition, each of the base view and the non-base view may be assigned with the NAL unit header MVC extension parameters including a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_ld), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an Inter-view prediction flag (inter_view_flag). [0029] In this way, a non-base view Is coded using various parameters. [0030] In addition, the computing NAL unit header MVC extension parameters for the base view may Include: obtaining a value of the non-IDR flag (non_ldr_flag) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the non-IDR flag (non_ldr_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the non-IDR flag (non_idr_flag) included in the NAL unit header MVC extension parameters of the base view; assigning a first predefined value to the priority ID (priority_id) included in the NAL unit header MVC extension parameters of the base view; assigning a second predefined value to the view ID (view_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the temporal ID (temporal_id) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the temporal ID (temporal_id) obtained from among the NAL unit header MVC extension parameters of the non-base view to the temporal ID (tempora_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the anchor picture flag (anchor_pic_flag) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the anchor picture flag (anchor_pic_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the anchor picture flag (anchor_pic_flag) included in the NAL unit header MVC extension parameters of the base view; and assigning a third predefined value to the inter-view prediction flag (lnter_view_flag) included in the NAL unit header MVC extension parameters of the base view. [0031] In this way, NAL unit header MVC extension parameters for a base view are specifically computed. [0032] In addition, an image coding method according to the present invention is for coding a multiview video, and may include: determining NAL unit header MVC extension parameters of a base view; determining NAL unit header MVC extension parameters of a non-base view; switching between writing and not writing the NAL unit header MVC extension parameters of the base view into prefix NAL units; writing the determined NAL unit header MVC extension parameters of the base view into the prefix NAL units when the switching is performed to write the NAL unit header MVC extension parameters of the base view into the prefix NAL units; coding an image of the base view; writing view components including the coded Image of the base view into NAL units; coding an image of the non-base view, using the determined NAL unit header MVC extension parameters of the base view and the determined NAL unit header MVC extension parameters of the non-base view; and writing view components including the coded image of the non-base view into NAL units. [0033] In this way, presence or absence of prefix NAL units can be switched in multiview video coding. In addition, load for computing NAL unit header MVC extension parameters for a base view is reduced. [0034] In addition, each of the base view and the non-base view may be assigned with the NAL unit header MVC extension parameters including a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag), and the determining NAL unit header MVC extension parameters of a base view may include: assigning a predefined first value to the priority ID (priority_id) included in the NAL unit header MVC extension parameters of the base view; assigning a predefined second value to the view ID (view_id) included in the NAL unit header MVC extension parameters of the base view; and assigning a predefined third value to the inter-view prediction flag (inter_view_flag) included in the NAL unit header MVC extension parameters of the base view. [0035] In this way, a non-base view is coded using various parameters. [0036] In addition, the computing NAL unit header MVC extension parameters for the base view may include: obtaining a value of a NAL unit type (nal_unit_type) from among NAL unit headers of the base view; assigning 0 to the non-IDR flag (non_idr_flag) included in the NAL unit header MVC extension parameters of the base view if the value of the NAL unit type (nal_unit_type) is 5; assigning 1 to the non-IDR flag (non_ilr_flag) included in the NAL unit header MVC extension parameters of the base view if the value of the NAL unit type (nal_unit_type) is 1; assigning a first predefined value to the priority ID (priority_id) included in the NAL unit header MVC extension parameters of the base view; assigning a second predefined value to the view ID (view_id) Included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the temporal ID (temporal_id) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the temporal ID (temporal_id) obtained from among the NAL unit header MVC extension parameters of the non-base view to the temporal ID (temporal_id) included in the NAL unit header MVC extension parameters of the base view; obtaining a value of the anchor picture flag (anchor_pic_flag) from among the NAL unit header MVC extension parameters of the non-base view; assigning the value of the anchor picture flag (anchor_pic_flag) obtained from among the NAL unit header MVC extension parameters of the non-base view to the anchor picture flag (anchor_pic_flag) Included in the NAL unit header MVC extension parameters of the base view; and assigning a third predefined value to the Inter-view prediction flag (inter_view_flag) included In the NAL unit header MVC extension parameters of the base view. [0037] In this way, NAL unit header MVC extension parameters for a base view are specifically computed. In addition, the use of the NAL unit header of a base view makes It possible to compute more precise values. [0038] In addition, the first predefined value assigned to the priority ID (priority_id) may be 0. [0039] In this way, a base view is handled preferentially. [0040] In addition, the second predefined value assigned to the view ID (view_id) may be 0. [0041] In this way, the view ID (view_id) of a base view is a distinguishable fixed value. [0042] In addition, the third predefined value assigned to the inter-view prediction flag (inter_view_flag) may be 1. [0043] In this way, a decoded image of a base view can be used for inter-view prediction. [0044] In addition, an image decoding apparatus according to the present invention is intended to decode a multiview video, and may include: a base view NAL unit parsing unit configured to parse NAL units including an image Included in view components of a base view; a base view decoding unit configured to decode the image included in the view components of the base view; a non-base view MVC extension parameter parsing unit configured to parse NAL unit header MVC extension parameters of a non-base view; a prefix NAL unit searching unit configured to search the view components of the base view for prefix NAL units; a base view MVC extension parameter computation unit configured to compute NAL unit header MVC extension parameters for the base view when no prefix NAL units are present in the view components of the base view; a base view MVC extension parameter parsing unit configured to parse, when prefix NAL units are present in the view components of the base view, the NAL unit header MVC extension parameters of the base view, with reference to the prefix NAL units; a non-base view NAL unit parsing unit configured to parse NAL units including an Image included in view components of the non-base view; and a non-base view decoding unit configured to decode the image included in the view components of the non-base view, using (i) the computed or parsed NAL unit header MVC extension parameters of the base view and (11) the parsed NAL unit header MVC extension parameters of the non-base view. [0045] In this way, a multiview video is decoded even when no prefix NAL units are used. [0046] In addition, an image coding apparatus according to the present invention is intended to code a nnultiview video, and may Include: a base view coding unit configured to code an image of a base view; a base view writing unit configured to write view components including the coded image of the base view into NAL units without using prefix NAL units; a non-base view MVC extension parameter determination unit configured to determine NAL unit header MVC extension parameters of a non-base view; a base view NAL unit header MVC extension parameter computation unit configured to compute NAL unit header MVC extension parameters for the base view; a non-base view coding unit configured to code an image of the non-base view, using the computed NAL unit header MVC extension parameters of the base view and the determined NAL unit header MVC extension parameters of the non-base view; and a non-base view writing unit configured to write view components including the coded image of the non-base view into NAL units. [0047] In this way, a multiview video is coded without using prefix NAL units. [0048] In addition, an Image coding apparatus according to the present invention is intended to code a multiview video, and may Include: a base view MVC extension parameter determination unit configured to determine NAL unit header MVC extension parameters of a base view; a non-base view MVC extension parameter determination unit configured to determine NAL unit header MVC extension parameters of a non-base view; a prefix NAL unit writing switching unit configured to switch between writing and not writing the NAL unit header MVC extension parameters of the base view into prefix NAL units; a prefix NAL unit writing unit configured to write the determined NAL unit header M\/C extension parameters of the base view into the prefix NAL units when the switching is performed to write the NAL unit header MVC extension parameters of the base view into the prefix NAL units; a base view coding unit configured to code an image of the base view; a base view writing unit configured to write view components including the coded image of the base view into NAL units; a non-base view coding unit configured to code an image of the non-base view, using the determined NAL unit header MVC extension parameters of the base view and the determined NAL unit header MVC extension parameters of the non-base view; and a non-base view writing unit configured to write view components including the coded Image of the non-base view into NAL units. [0049] In this way, presence or absence of prefix NAL units can be switched In multiview video coding. In addition, load for computing NAL unit header MVC extension parameters for a base view is reduced. [Advantageous Effects of Invention] [0050] According to the present Invention, a multiview video is coded and/or decoded even when no prefix NAL units are used. [0051] Accordingly, even a legacy AVC decoder Incapable of decoding a base view due to prefix NAL units can decode the base view included in a multiview video. In addition, It Is easy to add another view to a stream generated by coding a single view because no prefix NAL units are used. Furthermore, It Is easy to use a conventional bitstream generated by a legacy AVC encoder as a base view of a multiview video. [Brief Description of Drawings] [0052] [Fig. 1] Fig. 1 is a structural diagram of constituent elements of an image coding apparatus in Embodiment 1 of the present invention. [Fig. 2] Fig. 2 is a flowchart showing coding processing in Embodiment 1 of the present invention. [Fig. 3] Fig. 3 is a structural diagram of constituent elements of an image decoding apparatus in Embodiment 1 of the present invention. [Fig. 4] Fig. 4 is a flowchart showing decoding processing in Embodiment 1 of the present Invention. [Fig. 5] Fig. 5 is a flowchart showing processing to compute base view NAL unit header MVC extension parameters in Embodiment 1 of the present Invention. [Fig. 6] Fig. 6 is a diagram showing an example of the image coding apparatus in Embodiment 1 of the present Invention. [Fig. 7] Fig. 7 is a diagram showing an example of the Image decoding apparatus in Embodiment 1 of the present invention. [Fig. 8] Fig. 8 is a flowchart showing processing to compute base view NAL unit header MVC extension parameters in Embodiment 2 of the present invention. [Fig. 9] Fig. 9 is a diagram showing an example of an image coding apparatus in Embodiment 2 of the present Invention. [Fig. 10] Fig. 10 is a diagram showing an example of the image decoding apparatus In Embodiment 2 of the present Invention. [Fig. 11] Fig. 11 Is a structural diagram of constituent elements of an image coding apparatus in Embodiment 3 of the present Invention. [Fig. 12] Fig. 12 is a flowchart showing a variation of coding processing in Embodiment 3 of the present invention. [Fig. 13] Fig. 13 is a diagram slowing an example of an image coding apparatus in Embodiment 3 of the present Invention. [Fig. 14] Fig. 14 is a diagram showing an example of a data structure of a coded stream in each of the Embodiments of the present Invention. [Fig. 15] Fig. 15 schematically shows an overall configuration of a content providing system for Implementing content distribution services. [Fig. 16] Fig. 16 shows an external view of a cellular phone. [Fig. 17] Fig. 17 is a block diagram showing an example of a configuration of the cellular phone. [Fig. 18] Fig. 18 schematically shows an example of an overall configuration of a digital broadcasting system. [Fig. 19] Fig. 19 Is a block diagram showing an example of a configuration of a television. [Fig. 20] Fig. 20 Is a block diagram showing an example of a configuration of an information reproducing and recording unit that reads and writes information from and on a recording medium that is an optical disk. [Fig. 21] Fig. 21 shows an example of a configuration of a recording medium that is an optical disk, [Fig. 22] Fig. 22 is a block diagram showing an example of a configuration of an integrated circuit for Implementing the image coding method and the image decoding method according to each of Embodiments. [Fig. 23] Fig. 23 is a diagram showing the location of NAL unit header MVC extension syntaxes. [Description of Embodiments] [0053] New methods are introduced which include signaling parameters contained In the MVC extension part of the unit header of each prefix NAL unit to the MVC decoder without coding the prefix NAL unit in the compressed MVC stream. The present invention is novel in the point of allowing determination of the values associated with a base view of the coded MVC stream required to decode the corresponding non-base view without using prefix NAL units that may create a problem in the decoding process by a legacy AVC decoder. The present invention allows such legacy AVC decoders In the market to decode base views of MVC streams and also allows MVC decoders according to the present invention to decode all the coded views of the MVC streams. (Embodiment 1) [0054] First, Embodiment 1 is described. [0055] Fig. 1 Is a structural diagram of constituent elements of an Image coding apparatus In Embodiment 1 of the present Invention. [0056] The Image coding apparatus 150 shown In Fig. 1 includes a base view coding unit 100, a base view writing unit 102, a non-base view MVC extension parameter determination unit 104, a base view MVC extension parameter computation unit 106, a non-base view coding unit 108, and a non-base view writing unit 110. Each of the processing units executes a corresponding one of the following processes. [0057] Fig. 2 is a flowchart showing coding processing in Embodiment 1 of the present invention. [0058] First, the base view coding unit 100 codes a base view image (S100). The base view image is coded using the multiview video coding standard. The base view image coded using the multiview video coding standard can be decoded according to the Advanced Video Coding standard. [0059] Next, the base view writing unit 102 writes compressed base view components in NAL units (S102). The NAL units for the base view are filled without use of prefix NAL units as shown in Fig. 23. [0060] Next, the non-base view MVC extension parameter determination unit 104 determines NAL unit header MVC extension parameters of a non-base view (S104). Examples of these parameters Include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter view prediction flag (inter_view_flag). [0061] Next, the base view MVC extension parameter computation unit 106 computes NAL unit header MVC extension parameters of a base view (S106). Examples of these parameters Include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0062] The NAL unit header MVC extension parameters of the base view are stored In the MVC extension part of the NAL unit header of a prefix NAL unit in an assumed case where the prefix NAL unit Is used. [0063] Next, the non-base view coding unit 108 codes a non-base view image using the NAL unit header MVC extension parameters of the base view and non-base view (S108). [0064] Lastly, the non-base view writing unit 110 writes non-base view components in NAL units (S11O). [0065] Fig. 3 is a structural diagram of constituent elements of an image decoding apparatus in Embodiment 1 of the present invention. [0066] The image decoding apparatus 250 shown in Fig. 3 includes a base view NAL unit parsing unit 200, a base view decoding unit 202, a non-base view MVC extension parameter parsing unit 204, a prefix NAL unit searching unit 205, a base view MVC extension parameter computation unit 206, a base view MVC extension parameter parsing unit 207, a non-base view NAL unit parsing unit 208, and a non-base view decoding unit 210, Each of the processing units executes a corresponding one of the following processes. [0067] Fig. 4 Is a flowchart showing decoding processing in Embodiment 1 of the present invention. [0068] First, the base view NAL unit parsing unit 200 parses the NAL units of base view components (S200). [0069] Next, the base view decoding unit 202 decodes the base view image using the coding processing described in the multlview video coding standard (S202). [0070] Next, the non-base view MVC extension parameter parsing unit 204 parses the NAL unit header MVC extension parameters of the non-base view (S204). In other words, the non-base view MVC extension parameter parsing unit 204 obtains the non-base view MVC extension parameters by parsing the NAL unit header of the non-base view. [0071] Examples of these parameters include a non-IDR flag (non_icr_flag), a priority ID (priority_id), a view ID {view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0072] Next, the prefix NAL unit searching unit 205 searches for prefix NAL units of the base view (S205). [0073] Here, in the case where prefix NAL units of the base view are present in the base view (Yes in S205), the base view MVC extension parameter parsing unit 207 parses the NAL unit header MVC extension parameters of the base view, based on the prefix NAL units (S207). In other words, the base view MVC extension parameter parsing unit 207 obtains the NAL unit header MVC extension parameters of the base view, by parsing the NAL unit headers of the prefix NAL units. [0074] In the opposite case where no prefix NAL units of the base view are present in the base view (No in S205), the base view MVC extension parameter computation unit 206 computes NAL unit header MVC extension parameters of the base view (S206). [0075] Examples of these parameters include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0076] Next, the non-base view NAL unit parsing unit 208 parses the NAL units of non-base view components (S208). [0077] Lastly, the non-base view decoding unit 210 decodes the non-base view image using the NAL unit header MVC extension parameters of the base view and non-base view, according to the decoding specified by the multiview video coding standard (S210). [0078] Fig. 5 is a flowchart showing processing to compute NAL unit header MVC extension parameters for a base view In Embodiment 1 of the present invention. Examples of these parameters include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an Inter-view prediction flag (inter_view_flag). [0079] The following describes processing executed by the base view MVC extension parameter computation unit 106 of the Image coding apparatus 150. The base view MVC extension parameter computation unit 206 of the image decoding apparatus 250 executes the same processing. [0080] First, the base view MVC extension parameter computation unit 106 reads the value of the non-IDR flag (non_idr_flag) from among the NAL unit header MVC extension parameters of the non-base view (S300). [0081] Next, the base view MVC extension parameter computation unit 106 assigns the value of the non-IDR flag (non_idr_flag) of the non-base view to the non-IDR flag (non_idr_flag) of the base view (S302). [0082] Next, base view MVC extension parameter computation unit 106 assigns a predefined value to the priority ID (priority_id) of the base view (S304). The value predefined as the value of the priority ID (priority_id) is 0. [0083] Next, the base view MVC extension parameter computation unit 106 assigns a predefined value to the view ID (view_id) (S306). The value predefined as the value of the view ID (view_id) is also 0. [0084] Next, the base view MVC extension parameter computation unit 106 obtains the value of the temporal ID (temporal_id) of the non-base view from among the NAL unit header MVC extension parameters of the non-base view (S308). [0085] Next, the base view MVC extension parameter computation unit 106 assigns the obtained value of the temporal ID (temporal_id) of the non-base view to the temporal ID (temporal_id) of the base view (S310). [0086] Next, the base view MVC extension parameter computation unit 106 obtains the value of the anchor picture flag (anchor_pic_flag) from among the NAL unit header MVC extension parameters of the non-base view (S310). [0087] Next, the base view MVC extension parameter computation unit 106 assigns the obtained value of the anchor picture flag (anchor_pic_flag) of the non-base view to the anchor picture flag {anchor_pic_flag) of the base view (S314). [0088] Lastly, the base view MVC extension parameter computation unit 106 sets a predefined value to the inter-view prediction flag (inter_view_flag) of the base view (S316). The value predefined as the inter-view prediction flag (inter_view_flag) of the base view is 1. [0089] Fig. 6 Is a diagram showing an example of the image coding apparatus in Embodiment 1 of the present invention. This apparatus includes a base view coding unit 500, a base view writing unit 502, a base view decoding unit 504, a base view NAL unit header MVC extension parameter computation unit 506, a non-base view NAL unit header MVC extension parameter determination unit 508, a memory unit 510, a non-base view coding unit 512, and a non-base view writing unit 514. [0090] Firstly, a base view image D001 is input to the base view coding unit 500, and a compressed Image D003 is output to both the base view writing unit 502 and the base view decoding unit 504. The base view decoding unit 504 reads the compressed base view image D003, and outputs the decoded base view image D005 to the memory unit 510. [0091] As shown in Fig. 6, a non-base view image D011 is input to both the non-base view NAL unit header MVC extension parameter determination unit 508 and the non-base view coding unit 512. The non-base view NAL unit header MVC extension parameter determination unit 508 then outputs the NAL unit header MVC extension parameters of the non-base view D013 to both the base view NAL unit header MVC extension parameter computation unit 506 and the non-base view coding unit 512. The base view NAL unit header MVC extension parameter computation unit 506 obtains the predefined values D009 and the non-base view NAL unit header MVC extension parameters D013, assigns the values to the base view NAL unit header MVC extension parameters, and outputs the base view NAL unit header MVC extension parameters D017 to the non-base view coding unit 512. The non-base view coding unit 512 then obtains a non-base view image D011, the non-base view NAL unit header MVC extension parameters D013, the base view NAL unit header MVC extension parameters D017, and a decoded base view image D019, and outputs a compressed non-base view image D021. [0092] Lastly, the base view writing unit 502 obtains a compressed base view image D003 and outputs It as a compressed image D007 In a NAL unit, and the non-base view writing unit 514 obtains a compressed non-base view image D021 and outputs It as a compressed image D023 in the NAL unit. [0093] An Image coding apparatus shown In Fig. 6 is a specific example of the Image coding apparatus 150 shown in Fig. 1. The processing performed by each of the structural elements shown in Fig. 1 is executed by a corresponding one of the structural elements shown in Fig. 6. [0094] The processing of the base view coding unit 100 is executed by the base view coding unit 500. The processing of the base view writing unit 102 is executed by the base view writing unit 502. The processing performed by the non-base view MVC extension parameter determination unit 104 is executed by the non-base view NAL unit header MVC extension parameter determination unit 508. The processing performed by the base view MVC extension parameter computation unit 106 is executed by the base view NAL unit header MVC extension parameter computation unit 506. The processing of the non-base view coding unit 108 is executed by the non-base view coding unit 512. The processing of the non-base view writing unit 110 is executed by the non-base view writing unit 514. [0095] Fig. 7 is a diagram showing an example of the image decoding apparatus in Embodiment 1 of the present invention. The apparatus includes a splitter unit 600, a prefix NAL unit searching unit 601, a base view decoding unit 602, a base view prefix NAL unit header MVC extension parameter parsing unit 603, a memory unit 604, a switch unit 605, a non-base view NAL unit header MVC extension parameter parsing unit 608, a base view NAL unit header MVC extension parameter computation unit 606, and a non-base view decoding unit 610. [0096] As shown In FIG. 7, the splitter unit 600 obtains a compressed video D020 of one or more views, and divides it Into a compressed base view image D003 provided to the prefix NAL unit searching unit 601 and a compressed non-base view Image D021 provided to the non-base view NAL unit header MVC extension parameter parsing unit 608. The compressed base view image D003 is also output from the splitter unit 600 to the base view prefix NAL unit header MVC extension parameter parsing unit 603. The prefix NAL unit searching unit 601 searches the base view for prefix NAL units, and outputs a signal D016 indicating presence or absence of the prefix NAL units to the switch unit 605. The prefix NAL unit searching unit 601 also outputs the compressed base view image D004 to the base view decoding unit 602. [0097] The base view decoding unit 602 obtains the compressed base view image D004, and outputs a decoded base view image D005. The decoded base view image D005 is then stored in the memory unit 604. [0098] The base view prefix NAL unit header MVC extension parameter parsing unit 603 reads the compressed base view image D003, and outputs the base view NAL unit header MVC extension parameters D008 If prefix NAL units are present in the compressed base view. [0099] The non-base view NAL unit header MVC extension parameter parsing unit 608, obtains the compressed non-base view image D021, and outputs the non-base view NAL unit header MVC extension parameters D013 to both the base view NAL unit header MVC extension parameter computation unit 606 and the non-base view decoding unit 610. The non-base view NAL unit header MVC extension parameter parsing unit 608 also outputs the compressed non-base view Image D015 to the non-base view decoding unit 610. The base view NAL unit header MVC extension parameter computation unit 606 obtains the predefined values D009 and the non-base view NAL unit header MVC extension parameters D013, assigns the values to the base view NAL unit header MVC extension parameters, and outputs the base view NAL unit header MVC extension parameters D014 to the switch unit 605. [0100] Whether prefix NAL units are present in or absent from the compressed base view is determined based on a signal D016 signaled by the prefix NAL unit searching unit 601. If no prefix NAL units are present in the base view, the switch unit 605 passes the computed base view NAL unit header MVC extension parameters D014 to the non-base view decoding unit 610. If prefix NAL units are present, the switch unit 605 passes the parsed base view NAL unit header MVC extension parameters DOlO to the non-base view decoding unit 610. [0101] Finally, the non-base view decoding unit 610 obtains the decoded base view image D019, base view NAL unit header MVC extension parameters D010, parsed non-base view NAL unit header MVC extension parameters D013, and a compressed non-base view image D015, and outputs the decoded non-base view image D025. [0102] An image decoding apparatus shown in Fig. 7 is a specific example of the image decoding apparatus 250 shown in Fig. 3. The processing performed by each of the structural elements shown in Fig. 3 is executed by a corresponding one of the structural elements shown in Fig. 7. [0103] The processing performed by the base view NAL unit parsing unit 200 and the base view decoding unit 202 is executed by the base view decoding unit 602, The processing performed by the non-base view MVC extension parameter parsing unit 204 is executed by the non-base view NAL unit header MVC extension parameter parsing unit 608. The processing performed by the prefix NAL unit searching unit 205 Is executed by the prefix NAL unit searching unit 601. The processing performed by the base view MVC extension parameter parsing unit 207 Is executed by the base view prefix NAL unit header MVC extension parameter parsing unit 603. The processing performed by the base view MVC extension parameter computation unit 206 is executed by the base view NAL unit header MVC extension parameter computation unit 606. The processing performed by the non-base view NAL unit parsing unit 208 and the non-base view decoding unit 210 is executed by the non-base view decoding unit 610. [0104] As described above, the image coding apparatus 150 in Embodiment 1 codes a multiview video without using prefix NAL units. In this way, even a legacy AVC decoder that is incapable of decoding a base view due to prefix NAL units included in a coded multiview video can decode a base view. In addition, the image decoding apparatus 250 shown in Embodiment 1 can decode all the views included In the coded multiview video irrespective of whether or not the coded multiview video includes prefix NAL units. [0105] In addition, omitting prefix NAL units increases coding efficiency. [0106] It is noted that the image decoding apparatus 250 either parses the base view MVC extension parameters or computes base view MVC extension parameters, depending on the presence or absence of prefix NAL units. However, the image decoding apparatus 250 may decode a non-base view image by computing the base view MVC extension parameters from the non-base view MVC extension parameters Irrespective of the presence or absence of prefix NAL units. [0107] In this case, there is no need to include the prefix NAL unit searching unit 205, the base view MVC extension parameter parsing unit 207, and the processing executed thereby. The image decoding apparatus 250 is capable of decoding a coded multiview video even when (i) the image decoding apparatus 250 does not include such structural elements and (ii) the coded multiview video does not include prefix NAL units. [0108] The processing flows shown in Figs. 2, 4, and 5 are exemplary. Thus, the processing flows executed by the image coding apparatus 150 and the image decoding apparatus 250 are not limited to the processing flows shown in Figs. 2, 4, and 5. For example, the image coding apparatus 150 and the image decoding apparatus 250 may execute the processing shown in the respective diagrams in orders different from the orders of the processing shown in the corresponding diagrams, or otherwise may execute the processing shown in the respective diagrams in parallel. [0109] In addition, the predefined values to be assigned to the priority ID (priority_id), view ID (view_id), and inter-view prediction flag (view_inter_flag) may be values different from the values shown in Embodiment 1. [0110] In addition, there may be plural non-base views. (Embodiment 2) [0111] Next, Embodiment 2 Is described. [0112] An image coding apparatus 150 In Embodiment 2 Includes structural elements similar to those in the Image coding apparatus 150 In Embodiment 1 shown in Fig. 1. The image coding apparatus 150 In Embodiment 2 executes coding processing similar to the coding processing In Embodiment 1 shown In Fig. 2. An Image decoding apparatus 250 in Embodiment 2 includes structural elements similar to those in the image decoding apparatus 250 In Embodiment 1 shown in Fig. 3. The image decoding apparatus 250 in Embodiment 2 executes decoding processing similar to the decoding processing in Embodiment 1 shown in Fig. 4. [0113] Embodiment 2 is different from Embodiment 1 in the processing of computing NAL unit header MVC extension parameters for a base view. [0114] Fig. 8 is a flowchart showing processing to compute NAL unit header MVC extension parameters for a base view in Embodiment 2 of the present Invention. Examples of these parameters include a non-IDR flag (non_idr_flag), a priority ID (priority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0115] The following describes processing executed by the base view MVC extension parameter computation unit 106 of tine image coding apparatus 150. The base view MVC extension parameter computation unit 206 of the image decoding apparatus 250 executes the same processing. [0116] First, the base view MVC extension parameter computation unit 106 reads the value of a NAL unit type (nal_unit_type) from the NAL unit header of the base view (S400). [0117] Next, the base view MVC extension parameter computation unit 106 assigns 0 to a non-IDR flag (non_idr_flag) when the value of the NAL unit type (nal_unit_type) is 5 (S402). [0118] Otherwise, the base view MVC extension parameter computation unit 106 assigns 1 to a non-IDR flag (non_idr_flag) when the value of the NAL unit type (nal_unit_type) is 0 (S404). [0119] Next, base view MVC extension parameter computation unit 106 assigns a predefined value to the priority ID (priority_id) of the base view (S406). The value predefined as the value of the priority ID (priority_id) is 0. [0120] Next, the base view MVC extension parameter computation unit 106 assigns a predefined value to the view ID (view_id) (S408). The value predefined as the value of the view ID (view_id) is also 0. [0121] Next, the base view MVC extension parameter computation unit 106 obtains the value of the temporal ID (temporal_id) of a non-base view from the NAL unit header MVC extension parameters of the non-base view (S410). [0122] Next, the base view MVC extension parameter computation unit 106 assigns the obtained value of the temporal ID (temporal_id) of the non-base view to the temporal ID (temporal_id) of the base view (S412). [0123] Next, the base view MVC extension parameter computation unit 105 obtains the value of the anchor picture flag (anchor_pic_flag) from among the NAL unit header MVC extension parameters of the non-base view (S414). [0124] Next, the base view MVC extension parameter computation unit 106 assigns the obtained value of the anchor picture flag (anchor_pic_flag) of the non-base view to the anchor picture flag (anchor_pic_flag) of the base view (S416). [0125] Lastly, the base view MVC extension parameter computation unit 106 sets a predefined value to the inter-view prediction flag (inter_view_flag) of the base view (S418). The value predefined as the inter-view prediction flag (inter_view_flag) of the base view is 1. [0126] Fig. 9 is a diagram showing an example of the image coding apparatus In Embodiment 2 of the present invention. This apparatus includes a base view coding unit 700, a base view writing unit 702, a base view decoding unit 704, a base view NAL unit header MVC extension parameter computation unit 706, a non-base view NAL unit header MVC extension parameter determination unit 708, a memory unit 710, a non-base view coding unit 712, and a non-base view writing unit 714. [0127] First, a base view Image D001 is input to the base view coding unit 700, and a compressed base view image D003 Is output to both the base view writing unit 702 and the base view decoding unit 704. The base view decoding unit 704 reads the compressed base view Image D003, and outputs the decoded base view image D005 to the memory unit 710. The base view writing unit 702 obtains the compressed base view Image D003, and outputs the compressed base view images D007 in NAL units, and outputs the NAL unit type (nal_unit_type) value D018 of the base view NAL unit to the base view NAL unit header MVC extension parameter computation unit 706. [0128] As shown in Fig. 9, a non-base view Image D011 is input to both the non-base view NAL unit header MVC extension parameter determination unit 708 and the non-base view coding unit 712. The non-base view NAL unit header MVC extension parameter determination unit 708 then outputs the non-base view NAL unit header MVC extension parameters D013 to both the base view NAL unit header MVC extension parameter computation unit 706 and the non-base view coding unit 712. The base view NAL unit header MVC extension parameter computation unit 706 obtains the predefined values D009, the non-base view NAL unit header MVC extension parameters D013, and the NAL unit type (nai_unit_type) value D018 of the base view NAL unit, assigns the values to the base view NAL unit header MVC extension parameters, and outputs the base view NAL unit header MVC extension parameters D017 to the non-base view coding unit 712. The non-base view coding unit 712 then obtains a non-base view image D011, the non-base view NAL unit header MVC extension parameters D013, the base view NAL unit header MVC extension parameters D017, and a decoded base view image D019, and outputs a compressed non-base view image D021. [0129] Lastly, the non-base view writing unit 714 obtains a compressed non-base view Image D021, and outputs a compressed non-base view Image D023 In the NAL unit. [0130] An image coding apparatus shown in Fig. 9 Is a specific example of the image coding apparatus 150 shown In Fig. 1. The processing performed by each of the structural elements shown In Fig. 1 is executed by a corresponding one of the structural elements shown in Fig. 9. [0131] The processing performed by the base view coding unit 100 is executed by the base view coding unit 700. The processing performed by the base view writing unit 102 is executed by the base view writing unit 702. The processing performed by the non-base view MVC extension parameter determination unit 104 is executed by the non-base view NAL unit header MVC extension parameter determination unit 708. The processing performed by the base view MVC extension parameter computation unit 106 is executed by the base view NAL unit header MVC extension parameter computation unit 706. The processing performed by the non-base view coding unit 108 is executed by the non-base view coding unit 712. The processing performed by the non-base view writing unit 110 is executed by the non-base view writing unit 714. [0132] Fig. 10 is a diagram showing an example of the image decoding apparatus in Embodiment 2 of the present invention. The apparatus includes a splitter unit 800, a base view NAL unit header parameter parsing unit 802, a prefix NAL unit searching unit 803, a base view decoding unit 804, a base view prefix NAL unit header MVC extension parameter parsing unit 805, a memory unit 806, a switch unit 807, a base view NAL unit header MVC extension parameter computation unit 808, a non-base view NAL unit header MVC extension parameter parsing unit 810, and a non-base view decoding unit 812. [0133] As shown in Fig. 10, the splitter unit 800 obtains a compressed video D020 of one or more views, and divides it into a compressed base view image D003 provided to the base view NAL unit header parameter parsing unit 802 and a compressed non-base view Image D021 provided to the non-base view NAL unit header MVC extension parameter parsing unit 810. [0134] The base view NAL unit header parameter parsing unit 802 obtains the compressed base view image D003, and outputs the base view NAL unit type (nai_unit_type) value D018 to the base view NAL unit header MVC extension parameter computation unit 808. The base view NAL unit header parameter parsing unit 802 also outputs the compressed base view image D004 to the prefix NAL unit searching unit 803. The prefix NAL unit searching unit 803 searches the base view for a prefix NAL unit, and outputs a signal D016 indicating the presence or absence of the prefix NAL unit to the switch unit 807. The prefix NAL unit searching unit 803 also outputs the compressed base view image D006 to the base view decoding unit 804. [0135] The base view decoding unit 804 obtains the compressed base view image D006, and outputs a decoded base view Image D005. The decoded base view image D005 is stored in the memory unit 806. If prefix NAL units are present in the compressed base view, the base view prefix NAL unit header MVC extension parameter parsing unit 805 reads the compressed base view image D003, and outputs the base view NAL unit header MVC extension parameters D008. [0136] The non-base view NAL unit header MVC extension parameter parsing unit 810 obtains the compressed non-base view D021, and outputs the non-base view NAL unit header MVC extension parameters D013 to both the base view NAL unit header MVC extension parameter computation unit 808 and the non-base view decoding unit 812. The non-base view NAL unit header MVC extension parameter parsing unit 810 also outputs the compressed non-base view image D015 to the non-base view decoding unit 812. The base view NAL unit header MVC extension parameter computation unit 808 obtains the predefined values D009, the base view NAL unit type (nal_unit_type) D018 and the non-base view NAL unit header MVC extension parameters D013, assigns the values to the base view NAL unit header MVC extension parameters, and outputs the base view NAL unit header MVC extension parameters D014 to the switch unit 807. [0137] Whether prefix NAL units are present in or absent from the compressed base view is determined based on a signal D016 signaled by the prefix NAL unit searching unit 803. If no prefix NAL units are present in the base view, the switch unit 807 passes the computed base view NAL unit header MVC extension parameters D014 to the non-base view decoding unit 812. If prefix NAL units are present, the switch unit 807 passes the parsed base view NAL unit header MVC extension parameters D008 to the non-base view decoding unit 812. [0138] Finally, the non-base view decoding unit 812 obtains the decoded base view image D019, base view NAL unit header MVC extension parameters D010, parsed non-base view NAL unit header MVC extension parameters D013, and a compressed non-base view image D015, and outputs the non-base view decoded image D025. [0139] An Image decoding apparatus shown in Fig. 10 is a specific example of the image decoding apparatus 250 shown in Fig. 3. The processing performed by each of the structural elements shown in Fig. 3 is executed by a corresponding one of the structural elements shown in Fig. 10. [0140] The processing performed by the base view NAL unit parsing unit 200 and the base view decoding unit 202 is executed by the base view decoding unit 804. The processing performed by the non-base view MVC extension parameter parsing unit 204 is executed by the non-base view NAL unit header MVC extension parameter parsing unit 810. The processing performed by the prefix NAL unit searching unit 205 Is executed by the prefix NAL unit searching unit 803. The processing performed by the base view MVC extension parameter parsing unit 207 is executed by the base view prefix NAL unit header MVC extension parameter parsing unit 805. The processing performed by the base view MVC extension parameter computation unit 206 is executed by the base view NAL unit header MVC extension parameter computation unit 808. The processing performed by the non-base view NAL unit parsing unit 208 and the non-base view decoding unit 210 is executed by the non-base view decoding unit 812. [0141] As described above, the image coding apparatus 150 in Embodiment 2 codes a multiview video without prefix NAL units as in Embodiment 1. The image decoding apparatus 250 in Embodiment 2 is capable of decoding a coded multiview video irrespective of whether or not the coded multiview video includes prefix NAL units as In Embodiment 1. Furthermore, the image coding apparatus 150 and image decoding apparatus 250 in Embodiment 2 are capable of computing more accurate MVC extension parameters using base view NAL unit types when computing base view MVC extension parameters. [0142] As in Embodiment 1, the processing flow shown in Fig. 8 is exemplary. Thus, the processing flows executed by the image coding apparatus 150 and the image decoding apparatus 250 are not limited to the processing flow shown in Fig. 8. For example, the image coding apparatus 150 and the image decoding apparatus 250 may execute the processing shown in Fig. 8 in an order different from the order of the processing shown in Fig, 8, or otherwise may execute the processing shown in Fig. 8 in parallel. [0143] In addition, the predefined values to be assigned to the priority ID (priority_id), view ID (view_id), and inter-view prediction flag (view_inter_flag) may be values different from the values shown in Embodiment 2. [0144] Furthermore, there may be plural non-base views as in Embodiment 1. (Embodiment 3) [0145] Next, Embodiment 3 is described. [0146] Fig. 11 Is a structural diagram of constituent elements of an image coding apparatus in Embodiment 3 of the present invention. [0147] An image coding apparatus 950 shown in Fig. 11 includes a base view MVC extension parameter determination unit 900, a non-base view MVC extension parameter determination unit 902, a prefix NAL unit writing switching unit 904, a prefix NAL unit writing unit 906, a base view coding unit 908, a base view writing unit 910, a non-base view coding unit 912, and a non-base view writing unit 914. Each of the processing units executes a corresponding one of the following processes. [0148] Fig. 12 Is a flowchart showing coding processing In Embodiment 3 of the present invention. [0149] First, the base view MVC extension parameter determination unit 900 determines NAL unit header MVC extension parameters of a base view (S900). Examples of these parameters include a non-IDR flag (non_idr_flag), a priority ID (priority_ld), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_vlew_flag). [0150] Next, the non-base view MVC extension parameter determination unit 902 determines NAL unit header MVC extension parameters of a non-base view (S902). Examples of these parameters include a non-IDR flag (non_ldr_flag), a priority ID (prlority_id), a view ID (view_id), a temporal ID (temporal_id), an anchor picture flag (anchor_pic_flag), and an inter-view prediction flag (inter_view_flag). [0151] Next, the prefix NAL unit writing switching unit 904 switches between writing and not writing base view NAL unit header MVC extension parameters into the prefix NAL units (S904). For example, the prefix NAL unit writing switching unit 904 switches between writing and not writing the base view NAL unit header MVC extension parameters into the prefix NAL units, based on preset information. [0152] Here, in the case where the prefix NAL unit writing switching unit 904 switches to write the base view NAL unit header MVC extension parameters into the prefix NAL unit (Yes in S904), the prefix NAL unit writing unit 906 writes the base view NAL unit header MVC extension parameters into the prefix NAL unit (S906). [0153] In the opposite case where the prefix NAL unit writing switching unit 904 switches not to write the base view NAL unit header MVC extension parameters into the prefix NAL units (No in S904), the prefix NAL unit writing unit 906 does not write the base view NAL unit header MVC extension parameters into the prefix NAL units. In short, no prefix NAL units are generated. [0154] Next, the base view coding unit 908 codes a base view image (5908). The base view Image Is coded using the muitivlew video coding standard. The base view image coded using the multiview video coding standard can be decoded according to the Advanced Video Coding standard. [0155] Next, the base view writing unit 910 writes coded base view components in NAL units (S910). [0156] Next, the non-base view coding unit 912 codes a non-base view image using the NAL unit header MVC extension parameters of the base view and non-base view (S912). [0157] Lastly, the non-base view writing unit 914 writes non-base view components In NAL units (S914). [0158] Fig. 13 is a diagram showing an example of the Image coding apparatus In Embodiment 3 of the present Invention. This apparatus includes a base view coding unit 500, a base view writing unit 502, a base view decoding unit 504, a base view NAL unit tirade MVC extension parameter determination unit 1015, a non-base view NAL unit header MVC extension parameter determination unit 508, a memory unit 510, a non-base view coding unit 512, a non-base view writing unit 514, a switch unit 1016, and a prefix NAL unit writing unit 1017. [0159] The base view NAL unit header MVC extension parameter determination unit 1015 Is added instead of the base view NAL unit header MVC extension parameter computation unit 506 to the example shown in Fig. 6. The switch unit 1016 and the prefix NAL unit writing unit 1017 are further added thereto. [0160] The base view NAL unit header MVC extension parameter determination unit 1015 sets a value to the base view NAL unit header MVC extension parameter D017, and outputs the base view NAL unit header MVC extension parameters D017 to the non-base view coding unit 512. [0161] The non-base view NAL unit header MVC extension parameter determination unit 508 sets a value to a non-base view NAL unit header MVC extension parameters D013, and outputs the non-base view NAL unit header MVC extension parameters D013 to the non-base view coding unit 512. [0162] The base view Image D001 Is input to the base view coding unit 500, and a compressed base view image D003 Is output to both the base view writing unit 502 and the base view decoding unit 504. The base view decoding unit 504 reads the compressed base view image D003, and outputs the decoded base view image D005 to the memory unit 510. [0163] The non-base view image D011 is input to the non-base view coding unit 512. The non-base view coding unit 512 then obtains a non-base view image D011, the non-base view NAL unit header MVC extension parameters D013, the base view NAL unit header MVC extension parameters D017, and a decoded base view image D019, and outputs a compressed non-base view image D021. [0164] Lastly, the base view writing unit 502 and the non-base view writing unit 514 obtain a compressed base view image D003 and a compressed non-base view image D021, respectively, and output a compressed base view image D007 and a compressed non-base view image D023 in the NAL unit, respectively. [0165] In this way, a compressed video representing one or more views without prefix NAL units is generated. [0166] In the case where the setting is switched to include a prefix NAL unit, the switch unit 1016 outputs the base view NAL unit header MVC extension parameters D017 from the base view NAL unit header MVC extension parameter determination unit 1015 to the prefix NAL unit writing unit 1017. The prefix NAL unit writing unit 1017 writes the base view NAL unit header MVC extension parameters into the prefix NAL unit, and outputs the prefix NAL unit D022. [0167] In this way, a compressed video representing one or more views with such prefix NAL units is generated. [0168] An image coding apparatus shown in Fig. 13 is a specific example of the image coding apparatus 950 shown in Fig. 11. The processing performed by each of the structural elements shown in Fig. 11 is executed by a corresponding one of the structural elements shown in Fig. 13. [0169] For example, the processing performed by the base view MVC extension parameter determination unit 900 is executed by the base view NAL unit header MVC extension parameter determination unit 1015. The processing performed by the non-base view MVC extension parameter determination unit 902 is executed by the non-base view NAL unit header MVC extension parameter determination unit 508. The processing performed by the prefix NAL unit writing switching unit 904 is executed by the switch unit 1016. The processing performed by the prefix NAL unit writing unit 906 is executed by the prefix NAL unit writing unit 1017. The processing performed by the base view coding unit 908 is executed by the base view coding unit 500. The processing performed by the base view writing unit 910 is executed by the base view writing unit 502. The processing performed by the non-base view coding unit 912 Is executed by the non-base view coding unit 512. The processing performed by the non-base view writing unit 110 is executed by the non-base view writing unit 514. [0170] As described above, the image coding apparatus 950 in Embodiment 3 Is capable of switching the presence or absence of prefix NAL units in coding a multiview video. Furthermore, the image coding apparatus 950 in Embodiment 3 determines the MVC extension parameters of a base view and a non-base view. Stated differently, the image coding apparatus 950 Is not required to compute the base view MVC extension parameters. [0171] Furthermore, the image coding apparatus 950 is not required to determine the base view MVC extension parameters from the non-base view MVC extension parameters. The image coding apparatus 950 can use the base view MVC extension parameters determined Independently when coding the corresponding non-base view. [0172] Furthermore, even a legacy AVC decoder can decode the base view included In the coded multiview video as In Embodiments 1 and 2. The image decoding apparatus 250 In Embodiments 1 and 2 Is capable of decoding all the views included in the multiview video coded by the image coding apparatus 950. [0173] The image coding apparatus 950 switches between filling or not filling prefix NAL units. However, it nnay be assumed that the image coding apparatus 950 does not fill the prefix NAL units. In this case, there is no need to include the prefix NAL unit writing switching unit 904, the prefix NAL unit writing unit 906, and the processing performed thereby. [0174] As In Embodiments 1 and 2, the processing flow shown in Fig. 12 is exemplary. Thus, the processing flow executed by the image coding apparatus 950 is not limited to the processing flow shown in Fig. 12. For example, the image coding apparatus 950 may execute the processing shown In Fig. 12 in an order different from the order of the processing shown in Fig. 12, or otherwise may execute the processing shown Fig. 12 in parallel. [0175] In particular, the processing of determining the base view MVC extension parameters (S900) and the processing of determining the non-base view MVC extension parameters (S902) may be performed in the inverse order. It is only necessary that the processing of determining these MVC extension parameters (S900 and S902) is executed before the processing of coding a non-base view image (S912) and the processing of writing the MVC extension parameters (S906 and S914). [0176] As in Embodiments 1 and 2, the respective priority ID (priority_id), view ID (vlew_id), inter-view prediction flag (inter_view_flag) may be assigned with predefined values when the base view MVC extension parameters are determined (S900), For example, the priority ID (priority_id) is assigned with 0, the inter-view prediction flag (inter_view_flag) Is assigned with 0, and the inter-view prediction flag (inter_view_flag) is assigned with 1. [0177] Lil