1

GIMP's operations with color profiles seem hard to grasp.

I've studied a question describing experience similar to mine here: GIMP. TIFF. Color profile sRGB IEC61966-2.1 and embedded color profile GIMP - built-in sRGB

I appreciate that answers are technically deep and even develop a bit of an argument, but I'm struggling figuring out the proper strategy.

The embedded profile in my image is "PHL 246E7". I googled that, looks like it refers to a monitor model. Subquestion 1: what's the meaning of the relation between this image and this profile? Something like, "this image would have proper colors when displayed on this monitor, but not necessarily other monitors/printers"?

Then, @xiota recommends:

If the input file had a different profile, like Adobe RGB, you should convert to sRGB since you plan to use the images on the web.

I also plan to use the image on the web. But maybe this "PHL 246E7", whatever it is, is also sRGB, and I don't need any conversion (like @Tetsujin recommends). Subquestion 2. How do I find out whether this embedded profile is sRGB or not?

Then, there's recommendation from @Tetsujin:

I'd still always recommend only ever converting at export

At export in GIMP, I don't see any options explicitly suggesting the conversion of color profiles. I see GIMP has an ON/OFF checkbox to "Save color profile". If I check it, the image is saved having the same "PHL 246E7" embedded, as subsequent opening reveals. If I don't check, GIMP doesn't ask any questions on next opening, so I'm not sure what profile the result really contains, if any.

Subquestion 3: with this option OFF, would the result really be without color profile at all, or with GIMP's built-in sRGB?

Subquestion 4: if it's without, should I consider that to be "bad" for web usage and strive for embedding some color profile?

2

I can't answer this one with any certainty. The discussion (or argument:) you linked has 2 sides to the same reasoning, in effect.

This throws a spanner in the works of that reasoning because you should never embed a display profile in any image. The display profile should never even be in any workflow. That means this image is an unknown quantity whatever you do with it at import.

I would suggest experimenting.
Without making any other changes, convert one to sRGB at import, save as jpg. Then do the same again, converting only at export. See if you can spot any difference.
There may be differences you can't see, but as the display profile is an unknown quantity, just work with whichever looks good to you.

If the images come from a friend/colleague etc, get them to investigate colour workflow techniques for the future, or at least take their display profile out of their workflow.

1
  • 1
    But it looks good on my monitor! :)
    – xenoid
    Oct 14 at 8:01
1

The only time I come across an image with my monitor profile tagged is when it is a *screen capture... and my monitor profile is also an sRGB profile. But the color space tag is useless except on my computer; because, even if my sRGB monitor profile was exactly the same as the standard sRGB IEC61966-2.1 profile (only renamed), no other computer would know what my monitor profile is or have it installed with the same name.

You can check what profile is applied via menu Image>Image Properties>Color Profile. You can also set the title/status bar to display the image color space.

If color management is disabled (unchecked) Gimp applies an internal sRGB color space while editing... this is about the worst thing that can happen and the title/status bar will show "not color managed." In reality the color is being mismanaged...

You should enable color management and **convert any image that is not already sRGB into sRGB; Gimp's "built in sRGB" is exactly the same as sRGB IEC61966-2.1. So converting such an image is really just changing the naming convention of the color space tag.


*Using screen captures brings up the question of image sourcing and copyrights management/infringement IMO.

**You can use other color spaces such as ProPhoto w/in Gimp, but it becomes messy/fussy and you really need to know/understand what you are doing and why.

2
  • I'd wondered about this whilst composing my own answer. My screenshots embed my own display profile, but as I have a fully-calibrated workflow it seems to be 'OK'. My uncertainty is if this image came from someone else without calibration… though the profile can be 'decoded' on my Mac, the results would be random, as the input was.
    – Tetsujin
    Oct 15 at 9:40
  • In a fully managed system the last step is converting an image's colors to the monitor's colors via the correct color space (monitor profile). Because the image wasn't saved the data wasn't read from the original file and you essentially have a brand new picture with new exif and color space; as if it were captured with another camera (it effectively was). Because your monitor profile is on your computer it works fine in a color managed application. Oct 15 at 13:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.