1. Computer Graphics Tomas Vanicek College of Civil Engeneering, B407 vanicek@fsv.cvut.cz http://kix.fsv.cvut.cz/vanicek

2. Methods of graphical information saving Grid Vector

3. Grid formats

4. Colours in Computer Graphic

5. Electromagnetic Waves

6. Visible light Frequency 3.8×10 14 Hz až 7.5×10 14 Hz Wavelength 800nm – 400nm = 8-4×10 -7 m

7. Colour perception – Spectral function

8. Colour Models The spectral functions forms vector space of infinity dimension Human eye can recognize only 10.000 – 50.000 colour hues In fact only 3 dimensional vector space is usually sufficient We must chose 3 vector of base, 3 basic colour, for example Red (R), Green (G) and Blue (B)

9. RGB model

10. Aditive composition of colours

11. RGB – 8 basic colours

12. RGB – 256 colours 8 x 8 x 4 partion

13. RGB True Color 256 x 256 x 256 = 16.777.216 colours

14. CMY model Subtractive composition of colours

15. CMYK model Colour K made from CMY is not precise It is cheaper

16. Model HLS (Hue, Light, Saturation) Light S

17. Model HLS