Courtesy of Maureen Stone

1. Courtesy of Maureen Stone

2. Courtesy of Maureen Stone

3. Courtesy of Maureen Stone

4. Affects Lightness Scale Courtesy of Maureen Stone

5. Lightness Scales • Lightness: perceived reflectance • Brightness: perceived amount of light coming from a surface • Luminance: a measured value weighted by human spectral sensitivity • Varies with wavelength • Luminous efficiency function Green and blue lights of equal intensityhave different luminance values

6. L vs. Luminance Corners of the RGB color cube Luminance of these colors L from HLSAll the sameWrong! Modified from Maureen Stone

7. Value • Perceived lightness/darkness of a color • Scale from black to white • Power scale • Munsell value, L* • Single most important factor in color design Courtesy of Maureen Stone

8. Get it right in black and white • Value alone defines shape • No edge without lightness change • No shading with out lightness variation • Value difference defines contrast • Defines legibility • Use at least 3:1 luminance contrast for text clarity • Controls attention Modified from Maureen Stone

9. Controls Legibility Larry Arend, colorusage.arc.nasa.gov Drop Shadows Drop Shadow Need an edge Courtesy of Maureen Stone

10. Urgent Context Normal Normal Context Urgent Context Normal Urgent Context Normal Normal Context Normal Context Controls Attention, Clutter Courtesy of Maureen Stone

11. Window & Level Adjusts contrast in an image

12. Task: Find high & low anomalies http://www.jason.oceanobs.com/html/donnees/las/2005-03_uk.html

13. Task: Find high & low anomalies http://www.jason.oceanobs.com/html/donnees/las/2005-03_uk.html

14. Task: Understand relative height http://www.jason.oceanobs.com/html/donnees/las/2005-03_uk.html

15. Task: Find height 120 http://www.jason.oceanobs.com/html/donnees/las/2005-03_uk.html

16. Task: Identify the bananas apple banana peach plum

17. 3D Graphic Shading Interferes

18. Hard to distinguish, especially in small areas