#RGBA Structural Similarity
This tool computes (dis)similarity between two PNG images using (my approximation of) algorithms approximating human vision.
Comparison is done in L*a*b* color space† using SSIM algorithm.
It's a rewrite of Rabah Mehdi's C++ implementation:
- No C++ (C99)
- No OpenCV dependency (only
libpng) - Supports alpha channel
- Supports gamma correction
Values output are not comparable with other tools. This tool is meant to be simple and I'm not giving any guarantees about correctness (or speed :)
†) conversion assumes D65 white point and uses gamma from PNG file, defaulting to 2.2.
##Usage
dssim file.png file-modified.png
Will output something like 0.2341. 0 means exactly the same image, >0 (unbounded) is amount of difference.
dssim file.png file-modified.png totally-rad-visualisation.png
Will also output map of differences. Transparent areas will have funky pattern added.
##Build
You need libpng, zlib, pkg-config and make
make
Will give you dssim