Identify images with same content in Java

Question

A while ago, I spent some time searching for ways to determine whether two images are identical in order to answer this question. I now face a slightly different problem: I have

Answer 1

I think that the general answer to this question calls for an unsupervised machine learning approach that generates local invariant features - basically, a fancy way of finding hashes that don't change with scaling or rotation - and then running a clustering algorithm. Here are some papers that might be relevant:

• Clustering Near-Duplicate Images in Large Collections
• A Novel Duplicate Images Detection Method Based on PLSA Model
• Efficient image duplicate detection based on image analysis - Tons of stuff in here, since it's some dude's entire PhD thesis

Answer 2

Well i think dHash is something you need for this. You just have to improve dHash to take into consideration of rotation, that means 2000 images will be considered as 8000 images.

I wrote a pure java library just for this few days back. You can feed it with directory path(includes sub-directory), and it will list the duplicate images in list with absolute path which you want to delete. Alternatively, you can use it to find all unique images in a directory too.

It used awt api internally, so can't be used for Android though. Since, imageIO has problem reading alot of new types of images, i am using twelve monkeys jar which is internally used.

https://github.com/srch07/Duplicate-Image-Finder-API

Jar with dependencies bundled internally can be downloaded from, https://github.com/srch07/Duplicate-Image-Finder-API/blob/master/archives/duplicate_image_finder_1.0.jar

The api can find duplicates among images of different sizes too.