It's very hard navigating this website, so if I posted this in the wrong section, please move it to the correct one. Thank you! Since DigiKam keeps a fingerprint of each photo, and you can scan for duplicates. I am wondering if there will ever be a feature where you can input an image and it would scan the collection for that image. I have a large collection in the tens of millions, and none of the files are duplicates, but sometimes I need to go finding where the photo is saved on the computer and the filename and exif might be stripped, so I can only rely on the image itself being identical, etc. I'm imagining something as simple as the search field allowing for input of image and then it scans the collection.
As I understand your bug report, this function it already implemented - the similarity search. With the similarity search you can also drag an external image from the file manager onto the tab of the similarity search. DigiKam shows you whether it exists in your collection. Maik