Download - Characteristics and Limitations of Digital Color Photography

Characteristics and Limitations of Digital Color Photography

Harald BrendelMunich, 21 September 2012

Light is Electromagnetic Radiation

Short wavelength (~400nm)

Long wavelength (~700nm)

21.09.12 Harald Brendel, Arnold & Richter Cine Technik 2

Radiometry


Incandescent Light

Spectral Power Distribution


3200K

2000K

Incandescent Light


Daylight

5600K


6500K

Daylight


Photoreceptor


Retina

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


Color Receptors

x =


Tristimulus

Brightness

Color Sensation

21.09.12 11

Primary Colors


Additive Color Mixture


Additive Color Mixture: Red and Green

+


Additive Color Mixture: Blue and Green


Additive Color Mixture: Red and Blue


Additive Color Mixture: Red, Green, and Blue

Harald Brendel, Arnold & Richter Cine Technik 18

RGB forms White

=

=


Metamerism

Two Different Spectra

Same Tristimulus Values

Same Color Perception(For Average Observers)

Colors Are No Physical Attributes


Color Reproduction


Additive Display


Color Gamut

Spectral (monochromatic) locus

Primary colors

Mixtures of two colors

Mixtures of three colors


Digital Camera

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


Cameras See Different


Two Observers

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


Color Reproduction: Good


Color Reproduction: Bad


Color Reproduction: Ugly


Color Reproduction: Mission Impossible


A Camera Has No Gamut


Red Rose


Blue Lacquer


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.


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


Download - Characteristics and Limitations of Digital Color Photography

Top Related