Re: [Gimp-user] color management -- basic question

[Elle Stone <ellestone ninedegreesbelow com>]

On 01/10/2017 05:44 PM, Casey Connor wrote:

> I had planned to use
> Argyll/displaycal, and make a matrix profile per your suggestions. I
> think I read on your site that a LUT version would also be handy also
> for using occasional perceptual rendering intent to get a feel for all
> the detail in an image?

Yes, but depending on your monitor, normally it's better to not use the 
LUT profile for actual editing. And if you do use the LUT profile when 
editing, use relative colorimetric intent to convert to the monitor 
profile. Use perceptual intent for exploration, but not for editing, 
unless you know exactly what you are doing and why.

Truthfully I've only used my LUT monitor profile a couple of times to 
explore what might be hiding in the portions of an image that are 
clipped by a relative colorimetric conversion - in one image I was very 
surprised to see a whole lot of unexpected detail in areas that looked 
like there wasn't any detail at all.

> > So currently trying to soft proof to the built-in GIMP sRGB profile is
> > a waste of time as LCMS soft proofing will report that all the colors
> > are in gamut.
>
> Hmmm... so if I have a wide-gamut image and set soft-proofing profile to
> sRGB-elle-V4-srgbtrc.icc, soft proofing works -- that's because your
> version of gimp's sRGB is amended in the necessary ways to make it so?

Soft proofing to sRGB-elle-V4-srgbtrc.icc (which is the exact same 
profile as the GIMP built-in sRGB profile) also doesn't work. The 
problem is in LCMS, not in the profiles. All software that uses LCMS and 
supports high bit depth and floating point editing is affected, and all 
the more so if the source color space has a linear gamma TRC. Follow the 
links in the GIMP bug report for more information: 
https://bugzilla.gnome.org/show_bug.cgi?id=772266

Best,
Elle