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Feature #8461

openCL and rotate -> distortions

Added by Ulrich Pegelow about 8 years ago. Updated about 7 years ago.

Status:
Fixed
Priority:
High
Assignee:
-
Category:
General
Target version:
Start date:
Due date:
% Done:

100%

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

Description

I am using darktable 0.8+5~gd901c0c with openCL on NVIDIA GeForce GTS 450. There seems to be a bug when rotating images. With certain rotation angles the preview picture gets heavily distorted. I attach an input TIFF file and the corresponding screenshot as an example.

Some observations:
  • distortions happen around specific angles (e.g. +/- 3.75°)
  • zooming in removes distortions, zooming out brings distortions back
  • exported images (so far) are OK
  • changing the size of the input image to 90% leads to similar effect (1)
  • changing the size of the input image to 50% leads to distortions of the navigation window, not the preview itself

(1) I know about the issues with NVIDIA's openCL driver and its limitations in terms of picture size. So I am warned ;-)

Still I hope that the problem could be solved.

Ulrich

History

#1 Updated by Ulrich Pegelow about 8 years ago

I investigated a little bit further. My problem (i.e. magenta psychedelic
colors while rotating) was obviously introduced on 01. Feb with the commit of
color management in opencl. Versions prior to that don't show these artifacts.

#2 Updated by Ulrich Pegelow about 8 years ago

Further analysis lead to the finding that the problem is caused by color management in opencl with certain hardware (low to mid end NVIDIA cards, e.g.). Reason is an incomplete initialization of a matrix under certain run-time conditions. The attached patch is able to solve the issue.

#3 Updated by Simon Spannagel about 7 years ago

Hi Ulrich,

did you apply this patch so ticket can be closed?

#4 Updated by Ulrich Pegelow about 7 years ago

Replying to [comment:4 simn]:

Hi Ulrich,

did you apply this patch so ticket can be closed?

Yepp, it's solved and can be closed.

Ulrich

#5 Updated by Simon Spannagel about 7 years ago

  • Status changed from New to Fixed

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