[cairo] An Exercise In Cairo Operators

[Lawrence D'Oliveiro]

Objective: given an image, render it as though it were made up of
separate R, G and B elements of a given size and shape, arranged in a
regular grid.

Solution: <http://default-cube.deviantart.com/art/Shadow-Mask-533143786>

Source code:
<https://github.com/ldo/qahirah_examples/blob/master/shadow_mask>

The key to the solution was working entirely in opaque colours: alpha
transparency was irrelevant to this application.