VisiPics is a tiny, free application for Windows that will search for duplicate photos. You can find duplicate images using three different filters: (1) Strict (will return almost identical results - the image is the same or slightly different), (2) Basic and (3) Loose (with much more differences).
Additionally, you can also use the "Auto-Select" feature which will mark images with smaller, uncompressed, lower resolution copies as duplicates.
The program has other features such as a unignore, unselect (deselect), ignore the folders or files. This software will work with most major formats: JPEG, GIF, PNG, BMP, PCX, TIFF, TGA and RAW images. According to the author, the software has been tested with 100.000 pictures with a size of 15 GB and the results were available in approximately 3 hours.
Another advantage is the ability to delete duplicate files while the program is scanning for them - you don't have to wait to finish the scan. Although this program was made exclusively for Windows users, various other reviews claimed that the program runs great on Linux using Wine.
Note: This app uses ImageMagick (great app to manipulate most popular image formats) libraries to load pictures.
Important: Make sure that you backup your files and test the program on a small folder with just a few files. You have to understand how this tool works before any experiment takes place.
I know several reasons of why I would want to delete duplicate pics: space, multiple images made from different angles and the most disturbing - same image present in 2-3-4 folders on the same hard drive. The answer to this problem is a free software named VisiPics.
Download and install the application in seconds, and you will be enchanted by an intuitive, user-friendly interface.
Before you start using this application, please be careful at the following. This program uses it's own algorithm to identify duplicate images - not just duplicate file names.
Therefore, it will detect photos taken from a "slightly" different angle, and although for many people who want to keep only one copy (the one they like more) this is another great feature, others should consider this a warning if they want to keep all of them.
My recommendation for everyone would be to access the "Help" tab from the main interface and to read at least the "Tutorial - Basics" section which will take you less than 1 minute to understand how it works.
It contains two small paragraphs: how to "To start finding duplicate pictures" and "To delete your duplicates." I wanted to write about how to use this tool, but I would've "copy" the information found in its Help file.
Once again, I would like to repeat what I just said: backup your files, read the help file (it's small) and test the program.
As a conclusion, VisiPics is one of best options to remove duplicate images from your computer and if you find it useful, I am sure that the author will appreciate your donation.