Completing two points of my to-do list with
- added support for filtering with custom images
- added check for empty directories
Especially the first point felt really necessary to avoid doing a new release for every other new aggregator image...
Additionally, I discovered that duplicate checking (or technically any image comparison) isn't as flawless as I was hoping. Essentially, there may be false positives which is especially problematic for the duplicate check. As a temporary solution, I disabled duplicate checking by default and added a section to the readme explaining the issue in slightly more detail. It also includes a "workaround" on how to use the feature until I'm more confident in its reliability.
Finally, I did some other small fixes and optimizations...