To quickly adjust thumbnail size in the Album view, press and hold the Ctrl key, then use the mouse scroll wheel to make the thumbnails larger or smaller.
With the Non-Destructive editing and Versioning feature enabled, digiKam automatically hides originals and displays the latest modified versions of the photos. For example, if you process a NEF file and save it in the JPEG format, digiKam hides the original RAW file and shows only the JPEG photo. To disable this feature, choose Settings → Configure digiKam → Editing Images and make sure that the Always show original images option in the In main view section is enabled. To keep things tidy, you can then group the original and all its versions. To do this, select the photos you want to group, right-click on the selection, and choose Group → Group Selected Here.
If you receive the The trash has reached its maximum size! Cleanup the trash manually error message and emptying the Trash doesn’t help, then the following command may solve the problem:
Need to quickly locate all untagged photos? In digiKam, expand the Search left sidebar, and press the Advanced Search button. In the Advanced Search window, tick the Not Tagged check box and press OK to run the search.
Instead of the conventional thumbnail view, digiKam lets you map your photos on a globe. Choose View → Map, and you should see photos from the current album mapped on the 3-D globe.
You can then use the mouse to rotate the globe and the mouse wheel to zoom in and out. Obviously, the Map view displays only geotagged photos.