4 ms·

I believe the contrast adjustment was likely to get rid of any unwanted shades of grey before colouring the two extremes.

• jameshart 9y ago
  I suspect 'coloring the two extremes' involves something more like 'wiring the luminance signal up to the chroma'. Again, try not to think digital. This isn't photoshop, this is signal processing.
  • tomc1985 9y ago
    Or it could be a filter over the camera lens.
    • Jaruzel 9y ago
      Once you have a mostly Black, and White (with no greys) image - it's relatively simple via basic electronics to colour replace those with alternate colours - much like the old analogue chromakey 'blue-screen' techniques.