Its actually based on https://github.com/kyamagu/js-segment-annotator which implements two algorithm SLIC and PF.

Regarding compiling C using emscripten, I wanted a pure JS implementation so that it was hackable using Chrome Developer tools, E.g. using LAB data internally produced by SLIC algorithm. Hopefully in future, I will use a emscripten implementation. It might be important for version that proceses short gifs or videos.

Also there is a developer mode on top right, enabling it allows visualization of superpixels and change parameters of the algorithm.