Implementation of the H2SI (Hilbert square, super-importance) perceptual colour space.
This implementation is based on the paper "H2SI – A New Perceptual Colour Space" by Michael Nölle, Martin Suda, and Winfried Boxleitner. The colour space provides a metric that closely aligns with human color perception while maintaining mathematical properties suitable for algorithmic image processing.
The H2SI space represents colours using three complex numbers. These can be seen as triplet states of a three-dimensional quantum system or a three-dimensional normalised Hilbert space.