img pxl

Pxl pixelates into right-angled triangles. By default the “direction” of each triangle is determined by the “closeness” of the average colour in each quadrant.

Do not use antialiasing. If not using a square size this will make the result look bad.
Crop final image to exact triangles.
Use only left triangles.
Use only right triangles.
--cols <num>
Split into num columns.
--rows <num>
Split into num rows.
--size <HxW>
Specify the exact size to pixelate by (default: 20x20).

Based on the effect in pxl app, using the algorithm described in The pxl effect with javascript and canvas (and maths) by Dan Catt.