Placeholder for thoughts about Rubik’s Cube colourspace reduction for an art project.

Basics

I use a very simple palette: #fff #f00 #0f0 #00f #f80 #ff0

I have seen #FFFFFF, #000E98, #FF0000, #25C200, #F6FF00 #FF9C00 being used, too.

What’s difficult in this specific colour reduction exercise is that the convex hull of all available colours does not fill the entire RGB cube. The most important missing colour is black, but also cyan and magenta are missing. And yet we have orange, which is totally useless since we already have red and yellow: what did the Rubik’s Cube creators have in mind? Do they despise art so much?

Tests with existing software

Original image:

The Gimp

Results using Gimp’s ordered dithering ("Positioned"):

Results using "Floyd-Steinberg" and "Floyd-Steinberg (reduced color bleeding)" methods:

Floyd-Steinberg results after applying a 2.2 gamma correction:

ImageMagick

This is ImageMagick’s Floyd-Steinberg algorithm, on the original image and on a gamma-corrected image:

Links

​RubikCubism