Hi Remco,
I haven been reading a lot lately about this matter, and I think I'm
beginning to understand how it works. But, I'm still puzzled by
something like this:
I calibrated my monitor and I checked that DT is using the display
profile. Then, in DT, when I view this image of a poppy with that
display I see it like this:
http://pix.toile-libre.org/upload/original/1562447001.png
When I toggle the softproof which is set to either sRGB or AdobeRGB, I
see the image like this:
http://pix.toile-libre.org/upload/original/1562447215.jpg
I did not expect to see any difference, because they are both RGB and
the display profile is intended to also show RGB (99,5% AdobeRGB).
Why do I see this difference?
Op 12-06-19 om 07:56 schreef Remco Viëtor:
On mardi 11 juin 2019 21:57:55 CEST Kneops wrote:
I'm afraid I'm once more lost in the world of color (profiles).
I've read al lot in the manual about color settings, but just don't know
what the right settings need to be.
I have a Nikon D850 set to Adobe RGB, and I had my monitor calibrated
with Spider 4, and DT uses this icc file. I checked with darktable-cmstest.
The color in DT of a poppy was very vivid, with a a little magenta in
the red. I exported the image as sRGB for web and as Adobe RGB hirez.
Geeqie (also using the same monitor ICC) shows more red, less magenta.
Uploaded the image to Instagram and both in Firefox and Chrome the image
looks totally dull and darker and I removed the image immediately. As
far as I know both Chrome and Firefox can read the color profile of images.
What monitor profile should DT use? Adobe RGB? Or the ICC from Spider?
Should I unbreak the color profile (initially set to standard color
matrix) and set it manually to Adobe RGB?
Don't confuse *colour space* and *monitor profile*.
The colour space is *device independent* and describes what absolute colour a
given RGB triplet corresponds to. That's the one you select on export or as
"output colour profile". The best one to pick depends on what you want to do
with the image.
In an ideal world, the monitor should receive an RGB triplet and show the
proper colour. In practice, that's not quite the case. Worse, every monitor
can show a slightly different colour for a given RGB triplet.
So you need something to tell your system how a given RGB triplet should be
corrected for *your* particular monitor. That's what the display profile does.
The same reasoning holds for printing, which explains the enourmous number of
colour profiles you find there (one for every combination of printer, ink and
paper...).
As for the input colour profile: when using Raw files, it should be the
standard colour matrix (or a profile specifically created for your camera),
when using another file type, it should correspond to the file you use.
Your monitor profile should be the Spider one. But, afaik, most modern
operating systems allow you to set the display profile to use globally, and
that should be used by all programs. In that case there's no need to set a
display profile in dt or any other program (and this might even have a
negative effect, if it gets applied on top of the system profile).
Remco
P.S. Check your image for clipping in the red channel, in my experience esp.
red flowers like poppies are prone to that, due to the way the camera measures
the exposure combined with the high multiplication of the red channel in the
white balance setting.
Remco
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