050100150200250300 0 20 40 60 80 100 120 R+G+B vs. gray, LCD projector.
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Transcript of 050100150200250300 0 20 40 60 80 100 120 R+G+B vs. gray, LCD projector.
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More depth on Gamma
• Poynton, Gamma and its disguises: The nonlinear mappings of intensity in perception, CRTs, film and video. SMPTE Journal, 1993, 1099-1108
Halftoning
• The problem with ink: it’s opaque
• Screening: luminance range is accomplished by printing with dots of varying size. Collections of big dots appear dark, small dots appear light.
• % of area covered gives darkness.
Halftoning references
• A commercial but good set of tutorials• Digital Halftoning, by Robert Ulichney,
MIT Press, 1987
• Stochastic halftoning
Color halftoning
• Needs screens at different angles to avoid moire
• Needs differential color weighting due to nonlinear visual color response and spatial frequency dependencies.
Halftone ink
• May not always be opaque• Three inks can give 2^3=8 distinct colors• Visual system gives more since dot size,
spacing, yields intensity, gives somewhat additive system
• Highly nonlinear. See Berns et al. The Spectral Modeling of Large Format Ink Jet Printers
From http://www.matrixcolor.com/
108° 162°
90° 45°