A couple of months ago I started coding a little software in Processing. Nothing fancy, I was just trying to see what would have came out from a simple drawing editor, with the possibility of shaping a pixel perfect "brush" on a 9x9 pixel grid, and sampling the pixels color from the pixel of a "reference image" virtually situate under the drawing area, but invisible.
While the brush have a size range that can vary from 1 to 81 pixels, the sampling will always work only on 1 single pixel, the middle one.
The gesture is more like "to trace" than "to draw", and you'll end up with a "washed up" child of the reference image, but pixeled and sort of "empty". I'm still not sure on the results but since I won't have much time to work on it in the next few moths, I decided to share the process.
[ the software also include the possibility to sample RGB channels separately and vary the Alpha channel of the sampled pixel. The brush is editable realtime through a check box grid of 9 x 9 checks buttons. You can download the alpha .pde (v.0.4.1), but it's darn bugged! Sputt!_v.0.4.1]