- In signal processing, cross-correlation is a measure of similarity of two series as a function of the displacement of one relative to the other.
- Manhattan distance
- Bhattacharyya distance measures the similarity of two probability distributions.
- ImageHash which supports average hashing, perception hashing, difference hashing and wavelet hashing.
- dhash is a Python library which supports a perceptual hash based on Neal Krawetz’s dHash algorithm in this “Hacker Factor” blog entry.
- Differentiate images in python - get a ratio or percentage difference, and generate a diff image - Images should be the same size and have the same color channels (for example, RGB vs RGBA).