Chrominance Preservation issues [solved]

mosaster · April 21, 2019, 8:32am

Hello fellow photographers and OSS enthusiasts!
I am processing a bunch of RAWs with filmic (instead of the basic curve) module and want to retain full chrominance in the output. However the chrominance preservation failed dropping exposure values almost to pitch black.
I am sure I have correct exposure and tried this option on other images. At all times ‘chrominance preservation’ drives image underexposed
Here is a comparison of theoption off and on.
What might have caused the chrominance preservation to misbehave?

p.s. used this feature in DT 2.4.0 and it worked as expected

paperdigits · April 21, 2019, 8:42am

Have you tried to adjust the sliders manually? Pull the white relative exposure way down.

mosaster · April 21, 2019, 8:52am

Yes, I tried. Before posting here, every possible remedy I could think of and, surprisingly, moving white or black points wherever in filmic or exposure brings little to no effect.

You can see the filmic curve - it’s quite normal with no end point shifts.

Claes · April 21, 2019, 9:17am

Hi @mosaster,
Which dt version are you using?
Operating system?

paulmiller · April 21, 2019, 9:19am

This looks like a bug that was fixed in darktable 2.6.2

bc_the-path · April 21, 2019, 9:31am

It works fine in mine. DT 2.6.2 on Arch Linux, current.

mosaster · April 21, 2019, 9:47am

Hi, @Claes I am using 2.6.1 version

Claes · April 21, 2019, 9:59am

Hi!
Works fine here (I am on 2.7.0-git version).
Sounds as if you should try 2.6.2…

mosaster · April 23, 2019, 5:01am

Yes, it was an issue with DT version. Works normally with 2.6.2. Mystery solved!