Characteristics and Limitations of Digital Color Photography

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Characteristics and Limitations of Digital Color Photography Harald Brendel Munich, 21 September 2012

description

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. - PowerPoint PPT Presentation

Transcript of Characteristics and Limitations of Digital Color Photography

Page 1: Characteristics and Limitations of Digital Color  Photography

Characteristics and Limitations of Digital Color Photography

Harald BrendelMunich, 21 September 2012

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Light is Electromagnetic Radiation

Short wavelength (~400nm)

Long wavelength (~700nm)

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Radiometry

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Incandescent Light

Spectral Power Distribution

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3200K

2000K

Incandescent Light

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Daylight

5600K

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6500K

Daylight

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Photoreceptor

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Retina

http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html

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Color Receptors

x =

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Tristimulus

Brightness

Color Sensation

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Primary Colors

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Additive Color Mixture

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Additive Color Mixture: Red and Green

+

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Additive Color Mixture: Blue and Green

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Additive Color Mixture: Red and Blue

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Additive Color Mixture: Red, Green, and Blue

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RGB forms White

=

=

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Metamerism

Two Different Spectra

Same Tristimulus Values

Same Color Perception(For Average Observers)

Colors Are No Physical Attributes

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Color Reproduction

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Additive Display

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Color Gamut

Spectral (monochromatic) locus

Primary colors

Mixtures of two colors

Mixtures of three colors

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Digital Camera

http://en.wikipedia.org/wiki/File:Bayer_pattern_on_sensor.svg

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Cameras See Different

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Two Observers

Stimuli that look the same for one observermay look different for another

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Color Reproduction: Good

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Color Reproduction: Bad

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Color Reproduction: Ugly

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Color Reproduction: Mission Impossible

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A Camera Has No Gamut

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Red Rose

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Blue Lacquer

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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.

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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

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