Haskell Data Analysis Cookbook

Measuring image similarity with perceptual hashes

A perceptual hash produces a small digest from an image file where slight changes in the images only produce a slight change in the hash. This can be useful to quickly compare thousands of images.

Getting ready

Install the pHash library from www.phash.org. On a Debian-based system, we can install it by using apt-get as follows:

$ sudo apt-get install libphash0-dev

Install the phash library from Cabal as follows:

$ cabal install phash

Find three nearly identical images. We will use the following image:

This is the second image that we will be using

And the following image is the third:

How to do it…