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Characteristics and Limitations of Digital Color Photography. Harald Brendel Munich, 21 September 2012. Light is Electromagnetic Radiation. Long wavelength (~700nm). Short wavelength (~400nm). Radiometry. Incandescent Light. Spectral Power Distribution. Incandescent Light. 3200K.
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CharacteristicsandLimitationsofDigital Color Photography HaraldBrendel Munich, 21 September 2012
Light is Electromagnetic Radiation Long wavelength (~700nm) Short wavelength (~400nm) HaraldBrendel, Arnold & Richter Cine Technik
Radiometry HaraldBrendel, Arnold & Richter Cine Technik
Incandescent Light Spectral Power Distribution HaraldBrendel, Arnold & Richter Cine Technik
Incandescent Light 3200K 2000K HaraldBrendel, Arnold & Richter Cine Technik
Daylight 5600K HaraldBrendel, Arnold & Richter Cine Technik
Daylight 6500K HaraldBrendel, Arnold & Richter Cine Technik
Photoreceptor HaraldBrendel, Arnold & Richter Cine Technik
Retina http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html HaraldBrendel, Arnold & Richter Cine Technik
Color Receptors x = HaraldBrendel, Arnold & Richter Cine Technik
Tristimulus Brightness Color Sensation
Primary Colors HaraldBrendel, Arnold & Richter Cine Technik
Additive Color Mixture HaraldBrendel, Arnold & Richter Cine Technik
Additive Color Mixture: Red and Green + HaraldBrendel, Arnold & Richter Cine Technik
Additive Color Mixture: Blue and Green HaraldBrendel, Arnold & Richter Cine Technik
Additive Color Mixture: Red and Blue HaraldBrendel, Arnold & Richter Cine Technik
Additive Color Mixture: Red, Green, and Blue HaraldBrendel, Arnold & Richter Cine Technik
RGB forms White = = HaraldBrendel, Arnold & Richter Cine Technik
Metamerism Two Different Spectra Same Tristimulus Values Same Color Perception (For Average Observers) Colors Are No Physical Attributes HaraldBrendel, Arnold & Richter Cine Technik
Color Reproduction HaraldBrendel, Arnold & Richter Cine Technik
Additive Display HaraldBrendel, Arnold & Richter Cine Technik
Color Gamut Primary colors Mixtures of two colors Mixtures of three colors Spectral (monochromatic) locus HaraldBrendel, Arnold & Richter Cine Technik
Digital Camera • http://en.wikipedia.org/wiki/File:Bayer_pattern_on_sensor.svg HaraldBrendel, Arnold & Richter Cine Technik
Cameras See Different HaraldBrendel, Arnold & Richter Cine Technik
Two Observers Stimuli that look the same for one observer may look different for another HaraldBrendel, Arnold & Richter Cine Technik
Color Reproduction: Good HaraldBrendel, Arnold & Richter Cine Technik
Color Reproduction: Bad HaraldBrendel, Arnold & Richter Cine Technik
Color Reproduction: Ugly HaraldBrendel, Arnold & Richter Cine Technik
Color Reproduction: Mission Impossible HaraldBrendel, Arnold & Richter Cine Technik
A Camera Has No Gamut HaraldBrendel, Arnold & Richter Cine Technik
Red Rose HaraldBrendel, Arnold & Richter Cine Technik
Blue Lacquer HaraldBrendel, Arnold & Richter Cine Technik
Summary • Colors are no physical attributes. • Physically different stimuli can produce the same color sensation. • Two stimuli that produce the same color sensation may look different when photographed with a camera. • Two light sources that have the same color temperature may produce different object colors. • Digital cameras have no gamut. • The color encoding defines the gamut. HaraldBrendel, Arnold & Richter Cine Technik
Future Prospects • Cameras with spectral response more similar to the eye • Loss of dynamic range and sensitivity • Future sensor technology will compensate • Multi channel imaging • Scene encoding without gamut limits • Floating point numbers • Wide virtual primaries • AMPAS ACES HaraldBrendel, Arnold & Richter Cine Technik