Duplicate files of all types can be a problem, especially if you're running low on disk space. But duplicate photos bring their own challenges. Because of how we take and handle digital pictures, we tend to end up with multiple versions of the same photos, as well as separate but near-identical images.
For instance, your hard drive may contain an original, full-sized picture, and the smaller version you mailed to family. Or the original and the cropped one. And then there are light adjustments, conversions to black and white, and experiments with photo-editing tools. And let's not forget the near-identical pictures you take in your camera's burst mode. If you're trying to slim down your Pictures library, you'll want to be able to find all of these and decide which ones to keep.
I've tried a lot of duplicate file and photo finders over the years, and my current favorite--specifically for pictures--is the grandiosely-titled
Awesome Duplicate Photo Finder. It's free, simple, and it does a very good job of finding duplicates and not-quite duplicates.
It also comes in both installable and portable versions. You can run a portable program directly, without installing it first, and even carry it with you on a flash drive. That way, you can help friends slim down their collections, too.
After you load Awesome (I really hate that name), you simply drag your photo folders to the top part of the window, then click the big Start Search button. It took about twelve minutes to search through the 8,651 pictures in my library, where it found 483 possible duplicates.
Click on a set of two images, and you'll see both pictures, side by side. In between them, the program gives you a similarity percentage. 100% means you've got, not two versions of the same photo, but two copies of the same file. A low percentage usually means two similar photos, likely shot in the same location seconds apart.
I found Awesome able to recognize matched photos of different sizes, as well as ones where I'd adjusted the lighting or converted to black and white. It also found slightly cropped photos, but not heavily cropped ones.
Under each displayed picture, you'll find the file type, the resolution, and the file size. It doesn't show the file's location, but you can get that by either clicking the folder icon, or looking at the list of files below the picture.
You can probably guess what to do with the garbage can icon.
