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Bug #9973

Bad rendering in Darktable module: caused by edge threshold step in demosaic

Added by R - over 3 years ago. Updated over 3 years ago.

Status:
Confirmed
Priority:
Medium
Assignee:
-
Category:
-
Target version:
-
Start date:
05/28/2014
Due date:
% Done:

10%

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

Description

See attached screenshots which clearly illustrates the problem.

I simply opened the picture and adjusted the exposure and demosaicing algorithm (I prefer amaze).
The moment I changed the demosaic algorithm to amaze, purple dots appear all over the display.
They are there before, but much less noticable.
I viewed the RAW file in Geeqie and RawTherapee and neither one of them display the artifacts. RawTherapee uses the amaze algorithm too.

Exporting the file to JPEG does not show any artifacts.
If you would like the RAW file (~30MB), I can upload it upon request.

bad.jpg (346 KB) R -, 05/28/2014 06:57 AM

_RDG7164.jpg (6.36 MB) R -, 05/28/2014 06:57 AM

_RDG7164.NEF.xmp (5.55 KB) R -, 05/28/2014 10:10 AM

_RDG7164.NEF (29.9 MB) R -, 05/28/2014 10:10 AM

History

#1 Updated by Ulrich Pegelow over 3 years ago

Please supply RAW+XMP

#2 Updated by R - over 3 years ago

As requested.

#3 Updated by Ulrich Pegelow over 3 years ago

  • % Done changed from 0 to 10
  • Status changed from New to Confirmed
  • Subject changed from Bad rendering in Darktable module to Bad rendering in Darktable module: caused by edge threshold step in demosaic

There seems to be an issue with the edge threshold algorithm independent on whether PPG or AMAZE is used. The kind of artifacts varies depending on zoom level and also depends on CPU vs. GPU. Might be that the underlying algorithm has some numerical stability problems.

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