Clean out Your Duplicate Images
PhotoSweeper works with Aperture, iPhoto, and Adobe Lightroom libraries and image folders to find duplicates and look-alikes based on time interval or by comparing histograms or pixels.
You start the process by having the app create a catalog of your images—I used my collection of more than 6,500. (Note that you can save the catalog for later use.) After cataloging, decide which algorithm you want to use. Duplicates will find only exact duplicates on a byte-per-byte basis. Other methods, which resemble more or less the way you'd compare your photos, introduce some form of fuzziness.
I decided to go with the default setting, which is Time + Bitmap, where the interval between photos is taken into account, in addition to a visual similarity. If you want, you can change the bitmap size, the interval, RGB sensitivity, and other parameters to fine-tune the process, but the default settings gave me excellent results. When you're finished with the settings, click the Compare button. It took less than 10 minutes to compare my 6,500+ photos (using an iMac mid-2011 i5/16 GB).
After comparing the photos, PhotoSweeper marks the images it has identified as duplicates or look-alikes. You can then look at those images (grouped together in what the app thinks are a series of look-alikes) in the large thumbnail view, where you can uncheck any, if necessary. In my test, PhotoSweeper interpreted what "look-alike" means correctly about 95% of the time.
When you're finished going through all the marked and unmarked images, and making any changes, you can still restore them (in case you removed any accidentally) by clicking on the Trash icon to see which photos will be thrown out the window.
Company: Gwinno Software Inc.
Hot: Simplicity; accurate pattern-recognition algorithm; fine-tuning