I have about 8,000 JPEG photos, some of which are duplicates. Are there ways to identify and delete those duplicates?
DJ Leary        

There are a few third-party tools you can turn to. They include Hyperbolic Software’s $30 (£19) Tidy Up 2 (www.hyperbolicsoftware.com), Brattoo Propaganda Software’s $8 (£5) Duplicate Annihilator (www.brattoo.com/propaganda), Black Bilby’s $30 (£19) Duplicate Image Detector (www.blackbilby.com), Oliver Dreer’s free PixCompare (www.dreer.ch), and Lemkesoft’s $40 (£26) GraphicConverter 7 (www.lemkesoft.com).

Tidy Up 2 can search not only Aperture and iPhoto libraries but also any (or all) folders on your Mac. It can search by file type, EXIF data, and file attributes. Duplicate Annihilator comes in iPhoto and Aperture editions and can search for duplicates by MD5 checksum as well as by (among other things) creation date, width, height, and file size. When it finds duplicates, it can add a user-defined comment and move any duplicates it finds to iPhoto’s or Aperture’s trash.

Tidy Up 2 is one of several applications you can use to locate and deal with duplicate images

By default, Duplicate Image Detector won’t search an iPhoto or Aperture library. There is, however, an option to remove this restriction, though you must rebuild these libraries after you’ve removed duplicates from them. The program can search within folders for duplicate images as well as compare images in two separate folders and identify duplicates between those two folders. It bases its judgments on the images’ height and width. Once it has identified duplicates, you can trash, move, alias, or view them.

PixCompare will search in a single folder or two folders of your choosing. It rates the likeness of duplicates and allows you to preview the original and duplicate image. You can then trash the duplicate. GraphicConverter 7 has a feature for finding duplicates that you access by choosing Edit > Find, Compare And Replace > Find Duplicate Files. In the resulting Duplicate File Search window, you can ask the application to find exact matching files or similar files (and you can adjust a slider for more or less image similarity).