Legacy ImageMagick Discussions Archive

What's wrong with this world? djpeg9a (reference jpeg decoder) gives worse results - 344.225 (0.00525253) than libjpeg-turbo - this is the comparison for bmp decoded output. IM is the best and decodes with ABSOLUTELY NO errors. The problem was found - bad jpeg - jor jpeg9 and int dct for GIMP. If ...

I use only libjpeg-turbo library. roundoff issues shouldn't appear as GIMP (I posted a link to part of its source code) uses standard (default) values of libjpeg to open images.

Can this Arch Linux patch make the difference? https://projects.archlinux.org/svntogit ... jpeg-turbo

Maybe IM uses not the same system library (libjpeg-turbo) as GIMP. Gimp definitely not uses DCT conversion of lover quality - see https://git.gnome.org/browse/gimp/tree/ ... peg-load.c I mean it uses J_DCT_METHOD JDCT_DEFAULT

My OS is Arch Linux x86_64. RMSE gives result 69.3077 (0.00105757).

ImageMagick 6.9.0-0 Steps to reproduce: I want to compare 2 images https://upload.wikimedia.org/wikipedia/commons/d/d9/Constant_Troyon_-_Portrait_de_cheval.jpg and the same but converted to png (with no other changes). If I do: convert original.jpg original.png and then compare -metric PSNR original ...