As Simon correctly noted on Facebook, the app that I used to draw this picture is called Harmony by the amazing Mr. Doob.
I’ve made a few more. I love the look Harmony’s nearest neighbour stuff gives, but I have yet to really master it (although I have just ventured into colour). Finely detailed areas (such as eyes) are particularly difficult.
As always, click on the images for full-size versions (images below are only small sections of the originals):
Black and white is nice and all, but now for some colour! (I previously made a few other colour images, but they didn’t turn out so well…):
I like the sketchiness that Harmony gives. There’s no undo, but the lines are so thin that it’s more an exercise in either: getting it right (or close enough) the first time, or slowly accentuating what you would like to present.
It kinda matches the style of pencil drawings that I have been doing recently (when I watch online videos, like this – pretty bad – interview with Paul Krassner):
I’ll keep playing around with Harmony, but I want to work in colour a little more… but with nice gradients. Maybe I’ll have a look at the source code. More likely, I’ll just export a grey-scale image and then colourise in GIMP.
Update: Adding one more. Different approach.
I found that a good way to work is to start sketching in a light grey and then sketch over areas with increasingly dark greys (until hitting black).