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Bug #12331

Black spots when using sharpen, color zone, and exposure

Added by Benoit Brummer 8 months ago. Updated 8 months ago.

Status:
Closed: invalid
Priority:
Low
Assignee:
-
Category:
Darkroom
Target version:
Start date:
09/19/2018
Due date:
% Done:

0%

Affected Version:
git master branch
System:
other GNU/Linux
bitness:
64-bit
hardware architecture:
amd64/x86

Description

When using color zone to bring down the lightness of some overexposed bits (in this case neon lights), the final image has some black spots if the sharpen module is activated and the exposure is turned up.

DSCF6202.RAF - affected raw file (32.2 MB) Benoit Brummer, 09/19/2018 09:47 PM

(DSCF6202).jpg - example output (10.5 MB) Benoit Brummer, 09/19/2018 10:22 PM

DSCF6202.RAF.xmp - previous xmp (47.7 KB) Benoit Brummer, 09/20/2018 01:39 AM

DSCF6202_01.RAF.xmp - unbreak input profile technique (69.4 KB) Benoit Brummer, 09/20/2018 01:39 AM

History

#1 Updated by Benoit Brummer 8 months ago

example output attached

#2 Updated by Aurélien PIERRE 8 months ago

Reproduced here. You have to enable "clip gamut" [troncature du gamut] to sRGB in the input color profile module [profil de couleur d'entrée]. This is also dampened if you enable "5 passes" color smoothing [lissage des couleurs] in the demoisaicing module [dématriçage].

Finally, you shouldn't use a positive exposure compensation here (it's already overexposed by 1/3 EV), which will lead to clipped highlights and out-of-gamut colors (as you see).

The best practice here is to underexpose (with the exposure module) and fix the black point, then use the unbreak input profile module [correction du profil d'entrée] (thus, gamma correction) to bring back mid-tones in a safe way.

#3 Updated by Benoit Brummer 8 months ago

Thank you! That did fix it, and I tried the technique you mentioned and was able to recover more detail, although it took me more effort to get satisfying results (and I used some masks, I may be doing somethings wrong, the resulting jpg's are on https://commons.wikimedia.org/wiki/File:Manneken-Pis_1000th_costume_(DSCF6202).jpg and I uploaded both xmp's here in case you'd like to look at them, though I understand this isn't a help desk and I very much appreciate the help you've given me already!)

#4 Updated by Aurélien PIERRE 8 months ago

  • Status changed from New to Closed: invalid

I'm working on a simpler way to recover the dynamic range, with another mode for the unbreak input profile : https://discuss.pixls.us/t/solving-dynamic-range-problems-in-a-linear-way/9006/63

That should be easier and quicker in the future.

#5 Updated by Roman Lebedev 8 months ago

  • Target version set to 2.6.0

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