There are 2 repositories under similar-images topic.
Image similarity in Golang. Version 4 (LATEST)
Detwinner - duplicate file finder for the Linux desktop
Finding similar images from image URLs using ImageHash
Fast image similarity search with hash tables (Golang)
Source code for tutorial
image quantization program with 3 different quantization algorithms (Kmeans,median cut,uniform quantization) and another program works as similar images search engine
A desktop app that will help you find and deal with file duplicates on you drive
A Python package to detect and extract the changed parts & coordinates of those parts from the images if any.