graphics/dssim: add new port
This tool computes (dis)similarity between two or more PNG images
using an algorithm approximating human vision.
Comparison is done in L*a*b* color space (D65 white point, sRGB gamma)
using a multi-scale variant of the SSIM algorithm.
Features:
- Supports alpha channel
- Supports gamma correction
- No OpenCV or MATLAB needed:
- DSSIM version 1.x uses C (C99) and libpng or Cocoa on macOS.
- DSSIM version 2.x is easy to build with Rust