SirixDB is an an embeddable, bitemporal, append-only database system and event store, storing immutable lightweight snapshots. It keeps the full history of each resource. Every commit stores a space-efficient snapshot through structural sharing. It is log-structured and never overwrites data. SirixDB uses a novel page-level versioning approach.
Published on Maven Central Java Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison. Can be used for automation QA tests.