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Bug #12271

Enabling contrast, brightness and saturation grouping is affecting image

Added by Craig Parkinson 22 days ago. Updated 22 days ago.

Status:
New
Priority:
Low
Assignee:
-
Category:
Darkroom
Target version:
-
Start date:
07/24/2018
Due date:
% Done:

0%

Affected Version:
2.4.1
System:
Mac OS X
bitness:
64-bit
hardware architecture:
amd64/x86

Description

I've only noticed this on the attached RAW file, but in version 2.4.1 of Darktable, when you enable the brightness, contrast and saturation grouping tools the image histogram and preview is changed, even though no changes to the sliders have occurred. See the attached screenshots for an example.

IMG_9568.CR2.xmp (5.36 KB) Craig Parkinson, 07/24/2018 05:28 PM

Screen Shot 2018-07-24 at 15.20.46.png (3.15 MB) Craig Parkinson, 07/24/2018 05:30 PM

IMG_9568.CR2 (20 MB) Craig Parkinson, 07/24/2018 05:32 PM

History

#1 Updated by Christian Kanzian 22 days ago

I think that is per design.

darktable does not clamp color values to valid values by default. (https://www.darktable.org/usermanual/en/color_management.html#darktable_color_spaces)
Moduls are working in different color spaces and the conversion could cause such "artefacts" (https://www.darktable.org/usermanual/en/color_management.html#possible_color_artifacts).
The conversion takes place as soon as a single modul is turn on which is working in Lab color space.

You can try to turn on gamut cliping in the "input color profile" module like descripted in the manual or in this video tutorial:
https://www.youtube.com/watch?v=rkM9n7IkDR0

Does this help?

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