I’ve been working on a photo digitization project for several months now, and I think I’ve finally narrowed down an issue to digikam, but I can’t reproduce it consistently.
Here’s my workflow. I scan negatives or prints with Epson iScan into GIMP. There, I rotate, crop, clean up, and add “Description” metadata before exporting as a .png. The “Description” field in the GIMP metadata dialog saves to (at least) Exif.Image.ImageDescription (wrong, see below), and Iptc.Application2.Caption. I’m using thumbsup, and it will read the ImageDescription and display that with the image.
The problem is, after I finish scanning a batch, import the images into digikam, and add face tags so that thumbsup will create albums for people, about half of the exif descriptions stop showing up in thumbsup. Since thumbsup uses exiftool, I’ve been looking at the metadata with exiftool. For the images that no longer display a description in the thumbsup gallery, exiftool either doesn’t list Description any more, or it says it’s binary, and I need to use the -b option.
If I generate the html with thumbsup before adding face tags in digikam, all the Descriptions show up in the html gallery. After adding face tags, about half of them are gone, or binary according to exiftool and thumbsup. If I load the image into GIMP again, “Write Metadata” without making a change, and re-export the image. The Description works again in exiftool and thumbsup.
I started writing a rust program with rexiv2 to just copy the caption to the description, and it shows that the caption is still there, and sometimes the description is still there. Sometimes it’s changed to “Created with GIMP”
Note, I don’t use the metadata editor in digikam. I just show the face tags, and add face tags.
I think I’ve narrowed it down to something digikam is doing, but I can’t figure out if it’s a problem with my workflow, or a weird bug in digikam. I couldn’t find anything in digikam’s bug tracker.
So, is my workflow obviously stupid? Should it ever work? I still have lots more old photos and negatives to scan, so it would be nice to figure out what I’m doing wrong.
Edit: I lied. When I enter text in GIMP’s Description field in the Metadata dialog, it sets the Xmp.dc.description tag, and the Iptc.Application2.Caption tag, but NOT the Exif.Image.ImageDescription tag. Geeqie and exiv2 agree. exiftool just shows it once as “Description”