VisualPhotoCompare compares photos by visual content (content-based image retrieval) in a directory/drive and subdirectories. It can be used when you have a lot of images and you want to find duplicates, but it is possible that the size (width x height) of the photos is not the same.
First it lays an 8x8 grid on the photo. For 4 cells [3,3], [6,4], [4,6] and [7,7] an average RGB (red, green, blue) is calculated. This information goes to the work file. When comparing the lines in the work file 2 photos are the same if the differences between each R, G, B of the 4 cells are less then the setting of Max RGB difference.

The license of this software is Freeware, you can free download and free use this digital photo software.