Gwenview is a fast and easy to use image viewer by KDE, ideal for browsing and displaying a collection of images.
Features:
A lifesaver for me. I scanned several large SAAB service manuals using a smartphone on a tripod. I had to crop each of thousands of images to the same size but where the crop window would shift a little over time. This is the ONLY app I could find that made it feasible. Basically 3 or 4 inputs: Right arrow (get next), shift-c (crop func), optional adjust remembered window, alt-p (execute crop). Amazingly fast! So many thanks to the developers!