26 August 2013

GIMP modes

http://docs.gimp.org/2.8/en/gimp-concepts-layer-modes.html
M = mask (top), I = image (bottom)
  • normal: E = M
  • dissolve: E = M or I, randomly picked per pixel
  • multiply: E = M × I / 255
    • darker
  • divide: E = I × (256 / (M+1))
    • brighter, brightens dark M parts strongly
  • screen: E = 255 − (255 − M)(255 − I)/255
    • brighter, equiv. "multiply" conjugated by inversion
  • dodge: E = I × (256 / (256−M))
    • brighter, brightens bright M parts strongly; equivalent to divide with inverted mask
  • burn: E = 255 − (255 − I) × (256 / (M+1))
    • darker, darkens dark M parts strongly
  • hard light: super complicated
    • for M in [0,128] it's multiply with 2M; for larger M it's all conjugated with inversion
  • soft light: also complicated, I somehow doubt the documentation...
  • grain extract: E = I − M + 128
  • grain merge: E = I + M − 128
  • difference: E = |I − M|
  • addition: E = M + I
  • subtraction: E = I − M
  • darken: E = min
  • lighten: E = max
  • hue, saturation, brightness, value: takes that component from M and others from I

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