Sorry for all, I've mistaken.

I have taken careful view and see, they write in each square huge number of interference pictures - somewhere about 1M x 1M, and in calculation they consider 1Billion points with 4 colors in each, so just boolean true/false give close to 2^32 number of variants.

And there are 35,960 possible permutations, if use in each point 4 sources of light from 32 possible. These are reasonable considerations about possibilities of current technology.

This also not easy way, and I prefer to name it micro spectrogram.