Image Compression


IMAGE COMPRESSION
Many different image compression schemes exist, and several, often completely, different methods can be used for each of the different steps in an image compression scheme, and the different methods can often be combined in any way. Some examples are the Matlab implementation of SPIHT which is used as a reference compression scheme here. Also Matlab commands imwrite and imread supports several image formats, many of them include effective compression. The latest versions (from R2010b) also support the effective JPEG-2000 format (JP2 option). The standard JPEG format is also supported but the compression rate is not as good as expected, perhaps the overhead information is relatively large.
This page contains several Matlab functions, m-files, a brief explanation and some examples for image compression. The included functions can be used for some of the many steps or stages often done in image compression. It is not a complete finished codec, like JPEG or JPEG-2000. The stages presented here, section 2 to 6, are, with some variants, used in most image compression schemes. The more special method presented in section 7 can be used instead of, or in addition to, the transform part, section 3. Also several of these steps may be used for compression of other signals, or for other tasks in signal processing.








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