1. Colour Theory Helge Seetzen University of British Columbia helge.seetzen@sunnybrooktech.com Presentation and Outline at http:\www.sunnybrooktech.com\colour.html

2. Colour Theory Artist: Colour is a property of objects! Physicist: Colour is a property of light! Psychology: Colour is a property of our vision!

3. The Physicist: The Lightpipe LED Array Input Window Optical Lighting Film Mirrored Endcap Extractor

4. A colour circle, based on red, yellow and blue, is traditional in the field of art and is a way of arranging colours to show a variety of relationships between colours Sir Isaac Newton developed the first circular diagram of colours in 1666 The Artist: The Colour Wheel

5. wave? particle? ray? The Physicist: What is Light?

6. Wavelength - distance from peak to peak, or trough to trough Frequency - cycles per second; how many peaks pass a given point in 1 second The Physicist: Defining a Wave

7. The Physicist: Visible Spectrum

8. Mixing colours created by light. - Video Cameras - Computer Screens - Television Lights -Video Monitors Primary Colours - Red - Green - Blue The Physicist: Additive Colours

9. Additive Colours

10. The Physicist: But…

11. Used for mixing inks for printing. Primary colors are: - Yellow - Cyan - Magenta Subtractive Colours

12. The Physicist: Subtractive Colours

13. The Psychologist: And the Eye?

15. The Psychologist: Cone Sensitivity

16. Perception of monochromatic light of a laser at 640 nm The Psychologist: An Example

17. 640 photons The Psychologist: Incoming Light

18. Red cone is stimulated more than green cone The Psychologist: Stimulation

19. We have a perception of red The Psychologist: Perception

20. Perception of yellow light The Psychologist: Trickier Case

21. The Psychologist: Incoming Light Incoming light of 560-580nm

22. Red and green cone are stimulated equally The Psychologist: Stimulation

23. We have a perception of yellow The Psychologist: Perception

24. Colour: Bringing it all together =

25. Integration of each cone signal 5.5 1.5 0.3 =

26. Colour: There is a lot more to it! The ‘primary colours’ are A, B, and C. Then for a given real color, its components with respect to the primaries are as follows: x = A/(A+B+C) y = B/(A+B+C) z = C/(A+B+C) with x + y + z = 1 The CIE diagram is a plot of X vs. Y for all visible colors.