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Bug #11838

Demosaic match greens = "local average" trashes the image

Added by Mateusz Sebas 5 months ago. Updated 4 months ago.

Status:
Confirmed
Priority:
Low
Assignee:
-
Category:
Darkroom
Target version:
-
Start date:
11/28/2017
Due date:
% Done:

10%

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

Description

HEAD: bb388fdc0513c2564352b171dea27311da9b352a

Underexposed images with dark subject have a lot of white weird artifacts.
Artifacts look different in darkroom and in exported images (look at screens).
In light table they are seen only at maximum zoom.

Camera: Canon EOS M6

cat_sample.png - screenshot from darktable (521 KB) Mateusz Sebas, 11/28/2017 08:13 PM

IMG_4418.jpg - Exported (297 KB) Mateusz Sebas, 11/28/2017 08:14 PM

IMG_4418.CR2.xmp (3.39 KB) Mateusz Sebas, 11/28/2017 08:17 PM

IMG_4418.CR2 (29.7 MB) Mateusz Sebas, 11/28/2017 08:17 PM

cat_lighttable.png - Light table one stop before full zoom (137 KB) Mateusz Sebas, 11/28/2017 08:22 PM

cat_lighttable_2.png - Light table full zoom (676 KB) Mateusz Sebas, 11/28/2017 08:22 PM

Related issues

Related to darktable - Bug #11340: Demosaic outputs negative values In Progress 11/29/2016

History

#1 Updated by Mateusz Sebas 4 months ago

I've built current master: 83959cb0e0c86bf0c3cf2ee00834d71a8571a3a4 and I can still see white artifacts.

I think that this issue was not present in July when I bought the canon m6. It started to be visible when I did one of the upgrades of darktable, but I can't say when I did that.

I've tried to build older version of darktable from around July 2017 but I get (and then try to do bisect):

-- Performing Test C_COMPILER_UNDERSTANDS_-Wno-error=address-of-packed-member
-- Performing Test C_COMPILER_UNDERSTANDS_-Wno-error=address-of-packed-member - Failed
-- Performing Test CXX_COMPILER_UNDERSTANDS_-Wno-error=address-of-packed-member
-- Performing Test CXX_COMPILER_UNDERSTANDS_-Wno-error=address-of-packed-member - Failed

I've tried to use gcc 6 (ubuntu 17.10 has gcc 7), but looking at log from build.sh it seems that clang 3.9.1 (maybe older version is needed cause I am on newest ubuntu) is used. I quite don't understand c/c++ environment so its hard for me to debug this and build darktable from July.

#2 Updated by Roman Lebedev 4 months ago

  • System changed from Ubuntu to all
  • % Done changed from 0 to 10
  • Status changed from New to Confirmed
  • Subject changed from White artifacts on underexposed pictures on dark places to Demosaic match greens = "local average" trashes the image

Minimal reproducer: default empty history stack, and then in demosaic module set "match greens" to either "local average" or "full and local average".

#3 Updated by Roman Lebedev 4 months ago

  • Related to Bug #11340: Demosaic outputs negative values added

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