USE TURBO MODE Each pixel is rendered in only red, green or blue. Its intensity is set to the same intensity as the original pixel, and the choice of R/G/B is determined randomly, weighted by the individual RGB components, ie a pixel with twice as much blue than red is twice as likely to be rendered by blue than it is by red. Discussion here: https://scratch.mit.edu/discuss/topic/140162/?page=32#post-2021385
All credit to Gtoal
