Download and use these images you can open them in an app or your browser to see what rendering intent is used and if it recognizes the lut or only the matrix part of a profile…
If with “output profile” you mean the display profile, that should never be used as an export profile:
the display profile is there to correct between what your display claims to show for a given rgb triplet and what it actually shows for that triplet. As that correction is unique to your display, it should not be baked into the output file… (in an ideal world, you shouldn’t even have to tell darktable about your display profile, the OS should handle all that)…
The “profile” setting in the export module allows you to override the colour space you defined for the image in the darkroom, things like sRGB, AdobeRG, Rec2020, … That’s also what the “intent” refers to: what to do with colours outside the gamut covered by the selected colour space. As a display profile is a correction, the notion of “intent” isn’t relevant to it.
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Yes, but you set that colour space via the module output color profile, and one could simply call that profile the output profile. The setting in the export module, as you said, can be used to override the profile for a specific export.
https://darktable-org.github.io/dtdocs/en/module-reference/processing-modules/output-color-profile/
Yeah, that’s why I’m not really happy with the use of “profile” in darktable’s GUI where they mean “colour space”. But that’s a longer string, and there are only so many pixels available…
Perhaps I should have included your reply @thehatterman quoted.
@rvietor I did mean “output colour profile” when I said “output profile”. It is my understanding that the “output colour profile” is only involved in the export process, and is not another conversion before the display profile.
@kofa I am out of my depth as well, but I think I have a better understanding of the theory. Out of interest, if I softproof to your profile, I should see some subtle visual changes shouldn’t I ?
@priort thanks for the link, I will definately test that out over the weekend.
On a side note, I don’t think my installation of Firefox is correctly colour managed. Photos in the darkroom, gimp and the image viewer all look identical. Firefox looks a little darker and a little more saturated. ( I might open another thread if I can’t figure it out).
I think so. It’s a bit wider than sRGB, and it also has some curves. However, I never soft-proof to anything, so I really cannot tell.
@kofa neither do I, but I will try it out just out of interest really. I think soft proofing is meant for matching to print, so I might not see any obvious effect.
I dont think you will see much…if you want to download a paper profile and use that …the smaller gamut will show you the softproofing difference…I am not at home but I converted @kofa’s profile to xml and its a pretty good gamut most of P3 I think if I recall so you aren’t likely going to see much… at least I don’t think so…
@priort I will upload my .icc profile over the weekend, maybe tell me what you think?
So it’s soft proofing to a smaller gamut that shows a visual difference, that makes sense. I would need to install a CMYK profile wouldn’t I, as it is a smaller gamut? And I would expect the soft proof to display apparently brighter & less saturated ? The idea being that I re-edit accordingly?
Does this mean that you can’t actually print a photo and have it look (somewhat nearly) identical to that on screen (meaning not soft proofed) ? The printer gamut just might not be at all large enough ?
You can’t use CMYK with DT it doesn’t support it. I don’t print much but I don’t think you need it… RGB to CMYK conversion - #4 by priort
And really even with a good printshop from what I see people saying you will still need to do test prints to get it right or as good as it can be…
Not so much an issue with gamut as with physics: paper is reflective, a screen is emissive, so white is (much) brighter. Also colour mixing is subtractive on paper, and additive on display.
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The videos recently linked to in RGB to CMYK conversion - #4 by priort was elucidating in respect of the (no) need for CMYK, and the important impact of such a factor as the choice between glossy and matte paper.
Unless you know for a fact that you need CMYK, you don’t, and should stick to RGB.
This was (somewhat) covered in the RGB to CMYK conversion thread. But yes, any time you convert to a smaller gamut, colors will likely have to change in some way.
And the funny thing is, often gamuts (at least device gamuts, such as the respective gamuts of a display and a printer) are smaller in some aspect, and bigger in another, so it can happen that conversion cannot be done is a ‘lossless’ way, in either direction.
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I meant if I wanted to softproof against a printer, I would need it’s CMYK profile. However, having now watched the RGB to CMYK conversion videos in the link provided by priort, I now see I was talking rubbish.
If I want to softproof against a printer, I need its .icc profile (which is an RGB profile).
No, it’s not an RGB profile.
Roger that. It’s a device colour space defined in a .icc profile.
And afaik, those profiles are for printer/paper combinations, not just a printer.
Not illogical, given the variations between papers (texture, finish, base colour, …).
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@rvietor Roger that.
I have had a play with my new profile, and it looks good to me. You know, funny thing is I reverted back to the default profile ( which I beleive is automatically obtained from the EDID ) to compare, and I can get good results with that as well. It is highly likely that I don’t ( yet ) have an experienced enough eye to examine colours in a critical way.
I am glad that I threw myself into this over recent weeks, I have learned a lot, and not just about display profiles. I have found that I have a much more consistent expectation of the effects of various modules, and find myself making more subtle tweaks to tone and colour.
Thanks to all for helping, I have quite the reading list queued up now.
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In my opinion, the first step in display cal that has you adjusting the monitor using the monitor settings, gets you to a really good enough point. Mainly in the brightness at 120.
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