Use PixCompare to search for duplicates or similar pictures in a large collection of picture files, folders or the Photos app.

PixCompare Features
- Find duplicate and similar pictures in a folder full of pictures
- Find duplicates and similar pictures in Photos (requires macOS 10.15)
- Move pictures directly to the trash folder
- Display results as groups of similar pictures or as a list of similar pairs of pictures
- Compare one picture to a folder of other pictures
- Use macOS built-in Quicklook to display pictures in full size
- Works best on photographic pictures, file formats supported: JPEG, PNG, GIF, TIF, HEIC, and most RAW files.
- Search through up to 40,000 pictures
- Display up to 5,000 results

PixCompare can match two pictures even when:
- one of them is grayscale
- they don’t have the same size / aspect ratio
- the contrast / intensity is different
- they have a different pixel-depth
- and when one of them is blurred or rotated

Display results in two different result modes:
- Grouped Mode: Result pictures are displayed in groups of similar pictures.
- List Mode: Pairs of similar pictures are displayed in a list. The list is sorted by similarity score, i.e. the most similar pairs are at the top of the list.