If you happen to have lots of pictures and some of them look very similar or seem to be duplicates, you certainly need a program like Image Comparer. Basically, it is capable of scanning large amounts of image files and of finding exact copies or very similar pairs or groups. Then it can be set to delete them automatically for you, which will both save you a lot of time and help you recover wasted disk space.
The program includes a comparison wizard that launches every time you run the program. This will guide you step by step, making the comparison process much easier and quicker. Image Comparer uses the concept of "Galleries", which are the groups of images that the program will include in the comparisons. Thus, it provides two comparison options - within a single gallery or between two galleries. The wizard allows you to choose the comparison option, and to create your gallery or galleries, which may include one or more folders containing image files.
You can also choose if you want to locate similar images or just exact duplicates, and the name of the results file, which will be stored on your disk after the comparison process has ended. However, when you get more experienced with the program's usage, you can omit the wizard, and interact with the tools in the main interface directly. This allows you to easily open an existing gallery or to create a new one, to launch the comparison wizard, to see the previously-saved comparison results, to compact the contents of the currently open gallery (if applies) to save even more disk space, to execute new comparisons with the method of your choice, and to open the configuration window. When you open a gallery, you can perform additional operations, like adding more image files or entire folders to it, remove images from it or from the disk, or rename them. Here you have also an additional tab labeled "Image pairs", where you can see a report - as a list - with all the coincidences found, the name of both images, and the similarity percentage. The program is even capable of highlighting the differences between each pair of images when they exist.
Even though the functionality this program provides is fairly specific, it can really save you a lot of time and effort. The program offers you a 30-day trial version whose other limitation is that you cannot make use of its batch capabilities - useful when copying, moving or deleting many marked files.