X-Post https://www.reddit.com/r/photoshop/comments/5v4zid/issue_with_color_profiles_in_grayscale_images/ (slightly edited)

Hi everybody!

I hope the language barrier will not be noticed (feel free to point out mistakes).

I have an .psd-file created in Photoshop and I have several technical limitations for it. It is a grayscale image with 5 different grey values and no gradients or transparacy. Regardsless of any color profile (or even using none), it is not possible to me to find any setting to save the image and preserve the exact grayscale values at the moment. What seems to be right in Photoshop isn't right after parsing colors by code and/or isn't right if you look at it in another program (in my case GIMP). GIMP seems to handle those colors right everytime (while it doesn't have any color profiles assigned), so I wanted to know if there is a way to set Photoshop color profiles to anything similar?

Background information:

I can't attach any images, as they are related to my work, but you can reproduce a similar file like this:

  • New image: 512*512px; grayscale mode

  • Type: saved as *.tga-file

  • Content: areas filled only with solid colours (hard edges) (0; 81; 136; 194; 255)

Additional information:

  • Depending on the colour profile selected the colour values may vary (guess this is known to everybody who ever messed with it)
  • Without usage of any colour profile the colour values in photoshop and in GIMP (without colour profile too) are not the same (GIMP: 0; 32; 82; 156; 255)
  • I've found matching color values in both programs after setting mode from grayscale to RGB and saving in Photoshop, but this leads to a bigger file size (about 3 times as big)
  • Another funny thing I noticed was when I set the image to Indexed mode (just to see what happens) --> colors are matching those I've already seen in GIMP (0; 32; 82; 156; 255).

This issue is very confusing to me and I hope somebody can shed a light into the darkness of those grayscale values :P


Edit: Formatting

Edit #2: Just to clearify, with "no color profile" I am refering to whether the colors are transformed automatically between color spaces. I think here (https://forums.adobe.com/thread/368889) somebody has a rather similar issue and even there, there is no working solution (I tired any suggestions without any success).

Edit #3: I've figured out a workaround: create *.psd-file in RGB mode and save as *.tga file, as this will lead to the correct color values. Re-open the file in GIMP, convert to greyscale and save again. (Wow - the only working solution I got is to use another tool... a freeware that is known as a competitor to Photoshop)

  • If you do the math the ratio of log(x/255) between the two series of values is constant (about 1.8) so it looks like a gamma problem.
    – xenoid
    Feb 20, 2017 at 17:37
  • @xeniod That's likely. Question would still be if there is a way to set Photoshop color profiles to anything similar like GIMP at this point?
    – user86877
    Feb 21, 2017 at 9:13
  • I'm sorry I can't answer that because I don't use PS.
    – xenoid
    Feb 21, 2017 at 9:55


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