Title Repetition and Correlation Coding Technical Field The invention concerns a method for compressing Image data of an image. Cross-reference to related applications Title: REPETITiON CODED COIVIPRESSION FOR HIGHLY CORRELATED IMAGE DATA Application No.: PGT/IN03/00049 Filed: 7 March 2003 Inventor: Arvind Thiagarajan Title: COMPRESSING IMAGE DATA Application No.: PCT/SG2004/000411 Filed: 15 December 2004 Inventor: Arvind Thiagarajan Background of the invention Repetition Coded Compression (ROC) is a technology invented by the present inventor to increase compressibility of data. RCC is disclosed in the two previously filed cross-related applications, the contents of which are herein incorporated by reference. Using RCC, the data sequence is able to be compressed by 32% in this example. However, further compression is desirable. Summary of the invention In a first preferred aspect, there is provided a method for compressing image data of an image wherein the difference between each element and a previous element is calculated, the method comprising: comparing the difference with a predetermined correlation value and: if they are equai, a first value is recorded; and if they are not equal, a second value is recorded. The first and second values may be recorded in a bit plane. If first value is recorded, the value of the element may not be stored, and if the second value Is recorded, the value of the element may be stored. The method may further comprise associating the predetermined correlation value with the bit plane. The predetermined correlation value may be a value from -8 to +8. The method may further comprise repeating the comparison of the difference for each predetermined correlation value, and where a separate bit plane is used for each predetermined correlation value. The first value may be 1 and the second value may be 0. Each element may be a pixel. The method may further comprise the Initial step of: comparing each image element with a previous image element and if they are within a predetermined range of each other, modifying the image element to be equal to the previous image element; where repetition is increased to enable lossy compression of the image. The comparison may be performed in raster order, from left to right and then top to bottom. The comparison may be perfomed in non-raster order, the comparison being one from the group consisting of: vertical and diagonal. The method may further comprise transforming the image data according to any one from the group consisting: Repetition Coded Compression (RCC), Repetition Coded Oompresston Predict (RCCP), Repetition Coded Adaptive (RCCA), and Repetition Coded Compression Multidimensional. The method may further comprise dividing the image into a piurality of tiies. The method may further comprise streaming the tiles via a networlc. in a second aspect, there is provided a method for compressing data, the data comprising a plurality of data elements, wherein the difference between each element and a previous element is calculated, the method comprising: comparing the difference with a predetermined correlation value and: if they are equal, a first value is recorded; and If they are not equal, a second value Is recorded. In a third aspect, there is provided a system for compressing image data of an image wherein the difference between each element and a previous element is calculated, the system comprising: a comparison module to compare the difference with a predetermined correlation value, and if they are equal, a first value is recorded in a bit plane, and if they are not equal, a second value is recorded in the bit plane; and an encoder to encode first and second values in the bit plane into a bit plane index; wherein the compressed image is able to be decompressed using the bit plane index and the bit plane. The compressed image and bit plane may be stored on a storage medium and the compressed image is stored as a plurality of tiles to enable streaming of the compressed image. Brief Description of the Drawings An example of the invention will now be described with reference to the accompanying drawings, in v^ich: Figure 1 is an Illustration of an 81-pixel region within a sample of a colour image; Figure 2 is a graph illustrating the distribution of con'elation values for a typical colour image; Figure 3 is a process flow diagram of Repetition & Correlation Coding In accordance with a preferred embodiment of the present invention; and Figure 4 Is a system architecture diagram of the Repetition & Correlation Coding system in accordance with a prefen-ed embodiment of the present invention. Detailed Description of the Drawings The drawings and the following discussion are intended to provide a brief, general description of a suitable computing environment in which the present invention may be implemented. Although not required, the invention will be described in the general context of computer-executable instructions, such as program modules, being executed by a computer such as a personal computer, laptop computer, n6tebooi< computer, tablet computer, PDA and the \\ke. Generally, program modules Include routines, programs, characters, components, data structures, that perform particular tasl into a plurality of tiles. 14. The method according to claim 13, further comprising streaming the tiles via a network.. 15. The method as claimed in claim 4, further comprising encoding repetitions in the bit plane info a bit-plane index, and encoding image data values of the image data, to form compressed data. 16. A method for increasing compressibility of data, the data comprising a plurality of data elements, the method comprising: calculating a correlation between each data element and a previous data element; comparing the correlation with a predetermined correlation value and: if they are equal, a first value is recorded; and if they are not equal, a second value is reconded. 17. A system for compressing image data of an image wherein a corrlation between each image element and a previous image element is calculated, the system comprising: a comparison module to compare the correlation with a predetermined correlation value, and if they are equal, a first value is recorded in a bit plane, and if they are not equal, a second value is recorded in the bit plane; and an encoder to encode first and second values in the bit plane into a bit plane index; wherein the compressed image is able to be decompressed using the bit plane index and the bit plane. 18. The system according to claim 17, wherein the compressed image and bit plane are stored on a storage medium and the compressed image is stored as a plurality of files to enable streaming of the compressed image.