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Bug #10846

OpenEXR export looks too bright and colors are wrong

Added by Anonymous over 3 years ago. Updated over 3 years ago.

Status:
Incomplete
Priority:
Low
Assignee:
-
Category:
General
Target version:
-
Start date:
01/02/2016
Due date:
% Done:

20%

Estimated time:
Affected Version:
2.0.0
System:
Mac OS X
bitness:
64-bit
hardware architecture:
amd64/x86

Description

I tried the Darktable OpenEXR export and am wondering about the results.

How to reproduce:
1. Create an RGB 32 bit gamma floating point image in AdobeRGB (1998) in GIMP 2.9 and export it to TIFF and OpenEXR.
2. Import the TIFF image into DT and export it to OpenEXR.
3. Check these files in DJV image viewer.

Expected result:
I would expect the OpenEXR export look like the imported TIFF and colorimetrically correct.

Actual result:
The DT OpenEXR looks much brighter than the original and the GIMP OpenEXR export. The colors look wrong.

openexr testcase.zip (20.3 MB) openexr testcase.zip Anonymous, 01/02/2016 12:48 PM

History

#1 Updated by Roman Lebedev over 3 years ago

Do note that EXR can contain very limited colorspace information, so you need to manually verify that right color information is used.
Also, it is likely that GIMP 2.9 was still unable to read any colorspace information from EXR, you should retry with babl+gegl+gimp from git.

#2 Updated by Elle Stone over 3 years ago

As an aside, GIMP from git is GIMP 2.9.

One difference between the original tiff and the file exported from darktable is that the original tiff has negative RGB channel values. When exporting from darktable 2.0-rc3 (from Gentoo portage), the negative RGB channel values are clipped to zero even when gamut clipping is disabled. This is true regardless of whether exporting as a 32f tiff or as an EXR file.

I was careful to assign the same input and output ICC profiles for both GIMP and darktable.

#3 Updated by Tobias Ellinghaus over 3 years ago

  • % Done changed from 0 to 20
  • Status changed from New to Incomplete
  • Category changed from Lighttable to General

Did you try using a linear profile for the EXR?

#4 Updated by James C. McPherson over 3 years ago

  • Subject changed from OpenEXR export looks to bright and colors are wrong to OpenEXR export looks too bright and colors are wrong

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