The domino selfies
I am indebted to Laura Albert McLay who writes the Punk Rock OR blog for letting her readers know that they can use Bob Bosch's integer programming formulation for converting a picture into a piece of art using sets of dominoes. Bob uses sets of dominoes with up to 9 spots, rather than the more common limit of 6 spots. So this means that the "pixels" of dominoes can have 0 spots (black) through 5 spots (grey) to 9 spots (more or less white).
The tones of the original picture are converted to an integer in the range 0 to 9, and the model tries to match the spots of the dominoes to these numbers. The trouble is that every picture is constrained to use complete sets of dominoes, and the resulting art uses the whole of each domino in those sets. So each "pixel" is linked to another one, as the two ends of the domino. Laura gives the link for uploading your own picture in her current blog.
Try it yourself.
I started with a picture with a dark background, which meant that my face could be shaded with the greyer dominoes