CS781 - Colour for Computer Graphics - Winter 2009

Lecture 13

Creating Colour: Self-Luminous Devices

`Self-luminous' means producing light without an external illuminant.

Colour CRT

Colour CRT

What is it?

Usability tests

Calibrating a Colour CRT

Calibration

Characterization

Modelling a Colour CRT

The abstraction

  1. Three `phosphors' emitting light of constant chromaticity.
  2. Three `guns', each of which controls the intensity of light emitted by one of the phosphors
  3. Pixels are independent of one another
  4. Light output from phosphors depends only on the input to a single gun.
  5. Display surface has uniform characteristics
  6. Light output is stable over time

The colour gamut

The colour cube

The colour cube in colour space

The colour cube in chromaticity coordinates

Emitted colour

Emitted light

Tristimulus values

Measuring the Colour of CRT Output

Geometry

Problems

Building a Mapping

Model-based

Look-up Table Based

Calibrating a Colour CRT

The Television Signal

The White Axis

Gamma Correction

Colour LCD

Technological basis

What if we had four filters?

Colour OLED

Solid state photodetectors and LEDs are very closely related


Creating Colour: Illuminated Devices

Half-tone Printing

Photography

Continuous-tone Printing


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