func intensityToRGB(i int) (r int, g int, b int){
  region := i / 256
  remainder := i % 256
  switch region {
  case 0:
    r, b = 0, 255
    g = remainder
  case 1:
    r, g = 0, 255
    b = 255 - remainder
  case 2:
    g, b = 255, 0
    r = remainder
  case 3:
    r, b = 255, 0
    g = 255 - remainder
  }
  return
}