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Bug #10773

Built-in sRGB web-safe + LCMS2 produces unnaturally bright areas

Added by Istvan Kovacs over 3 years ago. Updated over 3 years ago.

Status:
New
Priority:
Low
Assignee:
-
Category:
General
Start date:
12/11/2015
Due date:
% Done:

0%

Affected Version:
2.0rc3
System:
Ubuntu
bitness:
64-bit
hardware architecture:
amd64/x86

Description

http://tech.kovacs-telekes.org/files/dt2-rc3-rendering/
Compare http://tech.kovacs-telekes.org/files/dt2-rc3-rendering/DSC_9526-nolcms2-sRGBwebSafe-perceptual.jpg and http://tech.kovacs-telekes.org/files/dt2-rc3-rendering/DSC_9526-withlcms2-sRGBwebSafe-perceptual.jpg
The tip of the pine twigs overhead, the blue area on the neck of the T-shirt of the 2nd-from-the-left girl, the coat of the 3rd-from-the-left girl appear too bright.
Exporting with the same settings but using e.g. sRGB_IEC61966-2-1_black_scaled.icc from http://www.color.org/srgbprofiles.xalter causes no such artefacts, the result is visually close to DSC_9526-nolcms2-sRGBwebSafe-perceptual.jpg no matter whether LCMS2 is turned on or off.

History

#1 Updated by Pascal Obry over 3 years ago

Cannot this be because some values are outside of the web-safe gammut and lcms does detect that? Is that affected by the intent chosen?

#2 Updated by Istvan Kovacs over 3 years ago

If the question is addressed to me - I have no idea. All I saw is the results of the exports, sRGB web-safe and the downloaded profile mentioned in the text, with/without LCMS2, with perceptual and relative rendering. Only the srgb websafe + LCMS2 exports showed this weird artefact.

#3 Updated by Tobias Ellinghaus over 3 years ago

If you are compiling darktable yourself you could try to change dt_colorspaces_create_srgb_profile to dt_colorspaces_create_srgb_profile_v4 in the file src/common/colorspaces.c, line 1256 and see if that fixes it.

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