You should think about adding a compare like program

[133794m3r]

As the title says, image magick's compare only uses PSNR, mse, ae, rsme and that's it. Since you support ssim(which should be the default as it's based upon how the human eye sees things compared to psnr). Having a simple tool to compare the images automatically would be a nice addition and also having cjpeg to output the ssim value for the image/other trellis that's been used.

So to just review here, mozjpeg is nice and all but since you've provided no easy program to compare images to show the differences with them in any easy way beyond comparing them blown up quite a bit and then staring at them with the human eye it's a great program but geting a comparison tool would be nice.

P.S. PNSR comparision shows that imgmin is clearly better, so is all other options that image magick's compare uses. And theirs is close to cjpeg except when using ssim with ssim the differences are about the same and in some spots slightly better but i'd rather not repeatedly sit there and compare it by hand. As your tool is the only one that uses ssim/trellis for compressing jpegs at this time.

P.P.S. Yes I realize it's mainly useful for the web as was imgmin but not providing details about the differences is a bad thing as it doesn't help someone compare the different trellis options with the image.

[danielgtaylor]

My jpeg-archive project includes a utility to compare using SSIM and MS-SSIM which you might find useful.

$ jpeg-compare --method ssim original.jpg compressed.jpg

$ jpeg-compare --method ms-ssim original.jpg compressed.jpg

It does not yet support arbitrary input formats, but I'm going to add PPM input soon.

Edit: as of https://github.com/danielgtaylor/jpeg-archive/commit/e0667cd82ff9bc5e5980392606955d4189704f59 it now supports PPM input of the first image via --ppm.