…as compared to the upstream TIFF and I don’t know if that’s expected or if I’m just doing something wrong. I’m certainly no expert in the realm of metadata, so I may well be doing something amiss.
I take a CR3 from my Canon T8i (850D), convert it to a TIFF in darktable 3.8.1 and then open the TIFF in GIMP 2.10.30 and export it as a JPG (all on Windows 11, BTW).
If I load both TIFF and JPG in GIMP and view the metadata, there’s a huge difference between the two files.
In other apps: FastStone image viewer it shows no EXIF for the JPG, nor do the DPReview forums if uploaded there. In XnVIew MP although the EXIF tab in the Properties panel is missing for the JPG, there’s data in the “Exiftool” tab (the differences of which are an unknown-to-me XnView implementation detail).
When I run exiftool against the TIFF and JPG, the JPG has a fraction of the EXIF entries in the TIFF. For what it’s worth, the TIFF has less EXIF than the raw file, but that’s related to darktable if anything.
I have all metadata export options enabled both in preferences and at export time. Am I doing something wrong? I’m not looking for anything fancy, just basic exposure / settings info from the camera.
If you want to look at the CR3, TIFF and JPG files, they’re here. There are also exiftool output captures for each file.
I just did a quick test with the provided RAW file:
Load RAW in darktable ( 3.9.0+411), no edits, export as 16bit uncompressed tiff
Load that tiff in GIMP (2.10.25) and keeping the profile that’s in the tiff, no edits, export as tiff, compression->none, did not select IPTC and GeoTIFF (others are ticked)
Ran exiftool and exiv2 (no options) on both output tiffs
Results:
There’s no difference when comparing the exiv2 output.
There are small differences when comparing the exiftool output.
a few entries are present in one but not the other and vice versa (276 vs 271 lines)
some entries have slightly different values
Both have a filled exif and exiftool tab in XnView
I also used Krita and RawTherapee to see if anything would be different: Yes, both of those only embed the most relevant tags (62/63 of them) and discards the rest.
I did use GIMP 2.10.25 and not the latest 2.10.30, so things might be different, but I do think that the tags exported are highly depended on the application and possibly even the version that is being used.
I just remembered that I still have GIMP 2.10.22, so compared the tiff exported from 2.10.22 with the one from 2.10.25 I see this:
Besides the obvious and expected differences (timestamps, gimp versions, document IDs etc) I see the following that is worth mentioning:
2.10.22 outputs 280 lines and 2.10.25 outputs 271 lines. So, 2.10.22 has some extra fields.
The biggest surprise: Even though my input file is a 16bit tiff 2.10.22 exports this one as a 367Mb 32bit float. The same one exported from 2.10.25 is exported as a 138Mb 16bit unsigned.
I did check the preferences for both versions and they are the same.
So, even 2 different minor version of GIMP give different metadata results (not counting the 16 vs 32 bit, although that is rather interesting and it does seem tiff related).