Comparing Images Fast!

David Oshiro, Hawaiian Hard Drive, Managing Editor

I'm always on the look out for utilities that can help me with my work. Last month, I was cleaning my hard drive; clearing out old files to make room for new files. I use Windows' built-in search feature to look for duplicates or files I no longer need by date or size. But I quickly ran into trouble when I discovered that I have a lot of duplicate images stored in my computer under different names and in different folders.

It turns out that I reuse a lot of images for web development and was storing a copy of each image in different folders. I did this because I like to keep all files for a particular project in its own folder. But doing this resulted in the same image being saved in 20 different places! I discovered that I was doing this with my digital photos as well.

Usually, when I create or manipulate graphics I convert it into the PhotoShop (PSD) format. When I am done editing the file I convert the file to JPG or GIF to be used on the web. The original file remains in PSD format if I need the original later. Now I have two files of the same image! After doing this for hundreds of images, sometimes changing the image multiple times, I ended up with multiple copies of the same image all over my hard drive.

Well, thank goodness I discovered a handy utility, called "Image Comparer", that searches for all the duplicate images I have scattered throughout my hard drive. The program's intelligent comparison engine allows it to determine if an image "looks" like another image. It can find the same picture no matter what the image format or dimension. it will even find rotated images!

The pictures I take with my digital camera are usually saved as JPGs. Image Comparer found multiple copies of the same image in JPG, PSD and GIF. Image Comparer was even smart enough to find similar looking photos. Like most people, I take multiple shots of the same scene with my digital camera. This is essential when taking group photos because you never know when someone might be blinking or doing bunny ears.

Normal file comparers simply look for exact matches. Once you change the file format, resize the image or add text to an image, the changed image is no longer identical to the original. Image Comparer actually "looks" at the image and determines how similar they both are. It generates a list of images by similarity.

Thanks to Image Comparer I was able to quickly go through hundreds of images and consolidate them to be deleted or backed up. If I had to search through my entire hard drive for all images then look at them one-by-one to determine if they were the same image, it may have taken weeks! I would recommend this tool for anyone who works with digital images. Image Comparer is produced by Bolide Software and is available via download for $19.95 (1.7Mb)