Originally forked from deepfryed/similie.

Phamilie is a simple DCT based image hashing interface that,

• computes a fingerprint based on low frequencies of an image.
• computes hamming distance between 2 fingerprints.

require 'phamilie'

phamilie = Phamilie.new

lena1 = 'spec/lena1.png'
lena2 = 'spec/lena2.png' # lena1.png cropped and scaled
lena5 = 'spec/lena5.png' # a different image
lena6 = 'spec/lena6.png' # lena2.png rotated and scaled

phamilie.fingerprint(lena1) #=> 36170087496991428

phamilie.distance(lena1, lena2) #=> 2
phamilie.distance(lena1, lena5) #=> 12

phamilie.distance(lena1, lena6) #=> 19
phamilie.distance(lena2, lena6) #=> 19
phamilie.distance(lena5, lena6) #=> 23
phamilie.distance_with_rotations(lena1, lena6) #=> 2
phamilie.distance_with_rotations(lena2, lena6) #=> 0
phamilie.distance_with_rotations(lena5, lena6) #=> 12

By default a Hash is used to cache fingerprints by path. Be carefull if images or current directory can change in process.

As cache you can use an instance of class responding to [] and []=.

If using persistant cache take into account file size and mtime or even cryptographic hash of contents.

• ruby 1.9.1+
• CImg
• libpng if you need to read png images
• libjpeg if you need to read jpeg images
• ImageMagick if you need to read other images

GPL — using code from pHash library