01-17-2019, 10:16 AM
I am using GIMP 2.10.8 on Linux and I have a problem with colour management. I work with RAW (NEF) files and use Darktable for RAW conversion. Most of my work is done in sRGB colour space so Darktable's output profile is set to sRGB (web-safe). In GIMP, Colour Management is enabled and the preferred RGB profile set to GIMP built-in sRGB.
The colours appear exactly as expected during the processing and the completed image is generally exported as a JPEG. The viewer I normally use is Gwenview. Here again the full-sized image is displayed as expected, but the thumbnails are much darker. If I look at the EXIF data in Gwenview I find there are not one, but two EXIF tags titled "Color Space" - one shows "Uncalibrated", the other "sRGB".
If I take a JPEG straight from the camera, both these EXIF tags show "sRGB" and the thumbnails display correctly. Subsequent processing in GIMP does not affect the EXIF tags or the thumbnail display in Gwenview. Exactly the same behaviour occurs with DigiKam as the viewer.
If before exporting from GIMP, I deliberately click Image -> Color Management -> Assign Color Profile it makes no difference to the situation described above. However, if I take the exported JPEG derived from the RAW file via Darktable and re-load it into GIMP, then add "Assign Color Profile", the thumbnails in Gwenview (or DigiKam) display correctly, but the two Color Space EXIF tags remain as "Uncalibrated" and "sRGB".
I am baffled by this behaviour, which is admittedly more of a nuisance than a serious problem, as each image displayed singly is fine and subsequent processing to print works perfectly. However, apart from the irritation of having very dark thumbnails displayed in the viewer I am concerned about the two conflicting EXIF tags and wonder whether this might cause a problem where the images are displayed on another computer, e.g. for competitions.
I would be very grateful for any explanation and hopefully a fix for this problem.
The colours appear exactly as expected during the processing and the completed image is generally exported as a JPEG. The viewer I normally use is Gwenview. Here again the full-sized image is displayed as expected, but the thumbnails are much darker. If I look at the EXIF data in Gwenview I find there are not one, but two EXIF tags titled "Color Space" - one shows "Uncalibrated", the other "sRGB".
If I take a JPEG straight from the camera, both these EXIF tags show "sRGB" and the thumbnails display correctly. Subsequent processing in GIMP does not affect the EXIF tags or the thumbnail display in Gwenview. Exactly the same behaviour occurs with DigiKam as the viewer.
If before exporting from GIMP, I deliberately click Image -> Color Management -> Assign Color Profile it makes no difference to the situation described above. However, if I take the exported JPEG derived from the RAW file via Darktable and re-load it into GIMP, then add "Assign Color Profile", the thumbnails in Gwenview (or DigiKam) display correctly, but the two Color Space EXIF tags remain as "Uncalibrated" and "sRGB".
I am baffled by this behaviour, which is admittedly more of a nuisance than a serious problem, as each image displayed singly is fine and subsequent processing to print works perfectly. However, apart from the irritation of having very dark thumbnails displayed in the viewer I am concerned about the two conflicting EXIF tags and wonder whether this might cause a problem where the images are displayed on another computer, e.g. for competitions.
I would be very grateful for any explanation and hopefully a fix for this problem.
