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2007.07.05 12:57 "Re: 16-Bit-Per-Channel Lossless Compression", by Andrey Kiselev
On Thu, Jul 05, 2007 at 01:03:07PM +0100, Andy Cave wrote: > I can easily do much better than that - 60:48. I can get ~21276876 > (~20M) and with some more work I think I can get down to 15-20M. Really? But how? > Andrey - since you have tiffcp built, can you repeat your test, but > produce tiled output? LZW and Flate. I think you'll find you get what Actually I did that --- without much success, so I have not listed these results. The full results: Original 60483984 ZIP, predictor 2 48095962 ZIP, predictor 2, separated 49303374 ZIP, predictor 2, tiled 47528554 ZIP, predictor 2, tiled, separated 49347802 So we can get better results with tiling, but nothing serious. Band separation doesn't help at all (though, I also thought that it should help). Those, who want reproduce this tests should get the GDAL library and use tool called gdal_translate, because tiffcp does not support band separation for 16-bit images. The command line to get tiled separated image is: $ gdal_translate -co "COMPRESS=ZIP" -co "PREDICTOR=2" -co "TILED=YES" -co "BLOCKXSIZE=256" -co "INTERLEAVE=BAND" IMG_2948.Flowers1.tif IMG_2948.Flowers1-zip2-tiled-sep.tif Best regards, Andrey -- Andrey V. Kiselev ICQ# 26871517