Visual Similarity Duplicate Image Finder is an inexpensive piece of software that can search your hard drive and find similar images and duplicate photos. This application finds similar pictures even if they are in different image formats or bit depths.
Whether your purpose is to free up space in your hard drive, or you just want to know how many versions of a certain photo you have made, the VSDIF can come in handy.
The Standard version is $25 while the Pro version, which adds support for scanning RAW formats from a number of different manufacturers as well as the DNG format, retails for $40.
If you wish to know how it works, thereâ€™s a review posted by Jon Canfield over at PhotographyBLOG.com; Jon gives us the nitty-gritty.