I use the imagemagick convert command to create thumbnails for the web from large images.

convert y2.psd[0] -resize '80x40' y2.png

Some images uploaded by a customer are CMYK Photoshop files with very large custom icc profiles. A 3Mbyte photoshop file turned into a 1.2Mbyte png file, even though the output png size was 80x40. The rest of the png file seems to have been profile information. When I run

convert y2.png -strip y2stripped.png

the file size goes down from 1.2Mbytes to 2kbytes.

I'm not too worried about including any profile information with the thumbnail, but I would like to know that the png has been properly produced and does reasonably represent the original image. I can't find any information on telling convert what color profile to use for the output image. Is color profile handling in convert well defined, please? How do I ask it to produce output with a specific color profile?

  • Thanks! That's a better explanation of the -profile and +profile options. However, it doesn't explain what imagemagick does with the profile. I can add or subtract profiles from the image file. But does that change the numbers stored for the color values of the pixels in the file? That's still not clear. – emrys57 Jan 29 '15 at 14:18
  • Re: see -profile. Maybe comparing before/after with identify -verbose shows something? You can also list the values for the colors in a palette; I just don't know if that's useful as I don't have any understanding of color profiles. If you figure it out, don't hesitate to provide an answer! Thanks! – user29318 Jan 29 '15 at 14:42

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