2018.06.08 00:17 "Re: [Tiff] LZ4 compression", by Even Rouault

On vendredi 8 juin 2018 00:02:46 CEST fx HAYAKAWA MICHIO wrote:

I successfully implemented LZ4 compression in libtiff on Windows platform. LZ4 frame format is used for compression scheme. LZ4 frame is widely used for various applications.

Does anyone have any test images to see LZ4 compression characteristics?

I also modified tiffcp to support LZ4, so that any tiff files can be converted into LZ4 tiff.

From my small experiments, its compression ratio is better than LZW, but worse than ZIP. Predictor is nicely working with LZ4. My tiff viewer shows LZ4 tiff very fast compared to ZIP especially large tiff files. If someone want the code, I'd like to pick up two TAG values before releasing it to avoid confusion.

#define COMPRESSION_LZ4         34926   /* LZ4 */

#define TIFFTAG_LZ4QUALITY              65564   /* LZ4 acceleration factor */

Are there any objections to pick up those values?

Yes! libtiff master uses 34926 for ZSTD codec: https://gitlab.com/libtiff/libtiff/blob/master/libtiff/tiff.h#L191

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