OpenEXR export looks too bright and colors are wrong
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.
I would expect the OpenEXR export look like the imported TIFF and colorimetrically correct.
The DT OpenEXR looks much brighter than the original and the GIMP OpenEXR export. The colors look wrong.
#1 Updated by Roman Lebedev about 4 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 about 4 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.