2014.12.20 23:06 "Re: [Tiff] Unnecessary bigger JPEG-compressed TIFF", by Even Rouault

Bob,

Have you compared JPEG-compressed TIFF output sizes with original JPEG files?

Perhaps GraphicsMagick (and ImageMagick) are doing something wrong, but TIFF with JPEG compression is looking a *lot* larger than original JPEG files:

Caused by my recent change?

freddy:~% gm convert seaworld.jpg -quality 90 crap.tiff
freddy:~% ls -l seaworld.jpg crap.tiff

-rw-r--r--   1 bfriesen home      939868 Dec 20 16:45 crap.tiff
-r--r--r--   1 bfriesen home      208903 Jun 12  2008 seaworld.jpg

Even using one strip per image makes little difference.

Perhaps due to -quality 90? You should make sure to use the same quality settings, and for the comparison to be fair, you should use the same input file.

And from my testing with old imagemagick it seems that gm convert doesn't produce a YCbCr JPEG-compressed TIFF.

With a converter I know better:

$ gdal_translate small_world.tif out.jpg -of jpeg

$ gdal_translate small_world.tif out.tif -co compress=jpeg -co photometric=ycbcr $ ll small_world.tif out.tif out.jpg

-rw-r--r-- 1 even even 14680 2014-12-21 00:00 out.jpg
-rw-r--r-- 1 even even 15694 2014-12-21 00:00 out.tif
-rw-r--r-- 1 even even 240574 2014-01-29 23:16 small_world.tif

Even

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