Darktable not reading the icc profile included in a TIFF file on import
Darktable does not seem to properly parse an the icc profile included a 16-bit TIFF file on import. The default input profile switches to sRGB (jpg) and uses that. If I use extracticc to extract the icc profile from the tiff, place the extracted icc profile in .config/darktable/colorin and select it in the colorin module, I get the proper colors. The issue seems to exist at least for both 16-bit tiffs generated by the Epson 4490 scanner software and the Sony Image Data Converter. The same tiffs read by other color aware linux software are parsed and displayed correctly, i.e. by the viewer Geeqie and RawTherapee. I suggest that the colorin profile should have an option to select the icc-profile from the input file and that using the included icc-profile should be selected by default, unless configured differently by a preset.
#1 Updated by Tobias Ellinghaus about 5 years ago
- System changed from Ubuntu to all
- Affected Version changed from 1.4.2 to git development version
- % Done changed from 0 to 20
- Status changed from New to Triaged
- Category set to Darkroom
- Tracker changed from Bug to Feature
Currently we only read embedded profiles from JPEG and JPEG2000 files. In order to support it for TIFF we would need a sample file with a profile attached. It doesn't need to be big and the actual content doesn't matter (it should however be obvious if the profile was applied or not when looking at the image, so some saturation might be needed).
#2 Updated by Gert van der Plas about 5 years ago
I've attached a zip file containing two jpegs and one tiff file generated by the Sony Image Data Converter. It has a included icc profile and the two included jpegs show the different saturation (particular the leaves) and some subtle weird color shifts in the shadows. The tiff should look like the proper jpeg in DT but looks like the improper jpeg. I did not include an epson scanner output. Let me know if you need one of them too. It takes a bit more time to get a 6x6 negative done.
#3 Updated by Tobias Ellinghaus about 5 years ago
- % Done changed from 20 to 100
- Status changed from Triaged to Fixed
Applied in changeset darktable|cf2aba65754bd1d1653f607a4cc558486dad5325.
#4 Updated by Long Wei almost 5 years ago
Does not seem to be fixed for epson profile.
See attached example and screenshot.
If I extract the ICC with extracticc from the file, place it in color/in and select from the list in the input color profil menu, it works (but I still have an error message on the screen)
#8 Updated by Long Wei almost 5 years ago
I have a lot of TIFF with this epson profile in my collection and before the implementation of the feature #10040, darktable was working fine, profile was not managed and darktable was switching automatically to sRGB, whithout any warning.
But now, as the epson ICC is not recognize, there is a persistent warning on both darkroom mode and lightable mode in the middle of the screen and the profile is switched automatically to Linear Rec709 RGB which is very very different from the initial one.
I think it would make sense to keep the initial behaviour in case the profile is not supported -> switch to sRGB.
#11 Updated by Pascal de Bruijn almost 5 years ago
Tobias is right, either Linear Rec709 or sRGB are both wrong, so a warning message is totally justified.
Supporting *Gray colorspace ICC profiles should be handled in a seperate feature request.
I've had a think about this, and if feasible I guess the following would probably be the least bad approach:
in case of RAW (when missing standard/enhanced matrix) -> Linear Rec2020 (not 709)
other cases -> sRGB
- Gray colorspace ICC's apparently define a Gamma curve, white- & blackpoint, and no XYZ color matrix.