How many pictures of Granny at Christmas do you really need? Or your dog doing something funny in the garden? The reality is we’ve all got too many photos and the prospect of sorting through them to work out which to keep and which to delete is so daunting that few of us bother.

We’ve recently discovered the PhotoSweeper application for Mac, which makes this seemingly huge task much easier and quicker.

PhotoSweeper looks at your iPhoto, Aperture or Adobe Lightroom photo libraries to find either exact duplicate photos or ones that are similar. It has lots of different settings that allow you to choose how it selects the pictures, and how it decides which to keep – for example you can pick partial matching based on the time the photo was taken, or the composition of the pictures. Once you’ve chosen the settings, PhotoSweeper makes a comparison of all the shots you’ve imported, and identifies groups of identical or similar pictures.

You can ask it to mark the one in each group that it ‘thinks’ is the best one, and delete the rest. If you really can’t face deleting them altogether, you can save them to a different folder.

PhotoSweeper is great for times when you’ve taken loads of pictures of the family, in the hope that everyone will be smiling in at least one of them, or when you’ve imported photos from other computers and cameras and you’re not sure whether you already have them in your library.

We spent a couple of hours last week using the app and got rid of almost 1500 photos from our library of 12,000 – saving around 3GB of space. That already makes it worth the £6.99 we paid for it.