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    Member cfeck's Avatar
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    iz: New fast lossless RGB photo compression

    Hi all, I finally managed to release a first preview of "iz" (ImageZero). Here some key stats:
    • should be similar in speed as "arc a -mmm:3*8+1xb"
    • compression rate similar to PNG for "good" photos
    • BSD license

    Caveats:
    • only designed for 24 bit RGB natural photos
    • compression of artificial images or very noisy images is bad
    • no grayscale mode
    • currently writes in machine-depended byte order, so files are not portable (they lack a header for now, anyway)

    Some technical details:
    • 3-pixel predictor
    • single context value
    • static Huffman tables (1 ... 6 bits per RGB pixel to encode context delta)
    • branchless design (there is only one branch for the per-pixel loop, and one branch in the bitcoder to flush bitcache to memory)

    More information:

    I am very interested in any kind of feedback, since I am new to this forum. Thanks, Christoph
    Last edited by cfeck; 19th March 2015 at 12:59. Reason: Moved from gitorious to github

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