A Python module for computing the Structural Similarity Image Metric (SSIM)
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Latest commit a44f23b Jul 8, 2016 @jterrace committed on GitHub Merge pull request #22 from asottile/patch-1
Explicitly list install requirements



This module implements the Structural Similarity Image Metric (SSIM). Original code written by Antoine Vacavant from http://isit.u-clermont1.fr/~anvacava/code.html, with modifications by Christopher Godfrey and Jeff Terrace.

Build Status


pip install pyssim


$ pyssim --help
usage: pyssim [-h] image1.png image path with* or image2.png

Compares an image with a list of images using the SSIM metric.
    pyssim test-images/test1-1.png "test-images/*"

positional arguments:
  image path with* or image2.png

optional arguments:
  -h, --help            show this help message and exit
  --cw                  compute the complex wavelet SSIM
  --width WIDTH         scales the image before computing SSIM
  --height HEIGHT       scales the image before computing SSIM


pyssim is known to work with Python 2.7, 3.4 and 3.5 and we test these versions on Travis CI to make sure they keep working.


To run from a local git client:

PYTHONPATH="." python ssim

To run the lint checks:

pylint --rcfile=.pylintrc -r n ssim setup.py

To test:

$ PYTHONPATH="." python ssim test-images/test1-1.png "test-images/*"
test-images/test1-1.png - test-images/test1-1.png: 1
test-images/test1-1.png - test-images/test1-2.png: 0.9980119
test-images/test1-1.png - test-images/test2-1.png: 0.6726952
test-images/test1-1.png - test-images/test2-2.png: 0.6485879


  • [1] Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli. Image quality assessment: From error visibility to structural similarity. IEEE Transactions on Image Processing, 13(4):600--612, 2004.
  • [2] Z. Wang and A. C. Bovik. Mean squared error: Love it or leave it? - A new look at signal fidelity measures. IEEE Signal Processing Magazine, 26(1):98--117, 2009.
  • [3] Z. Wang and E.P. Simoncelli. Translation Insensitive Image Similarity in Complex Wavelet Domain. Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on , vol.2, no., pp.573,576, March 18-23, 2005