1. Version 0.10 (c) 2007 CELEST VISI  N Star Light, Star Bright, Let’s Explore Light Using a Model How many black dots can you count?

2. Version 0.10 (c) 2007 CELEST MODELS The most abstract models are mathematical representations where variables represent realities. We can develop a better understanding of vision using models. A model is an abstract representation of an everyday experience. Some models look very similar to what they represent, other models are more abstract--like a diagram of the situation.

3. Version 0.10 (c) 2007 CELEST = ILLUMINATION, REFLECTANCE, AND BRIGHTNESS R(a) = E1E1 I1I1 Illuminance: I 1 Luminance: E 1 a R = E I Brightness constancy is due to discounting the illuminant. In general: Reflectance = Luminance Illuminance The reflectance has the same value under different lighting conditions. = E2E2 I2I2 Illuminance: I 2 Luminance: E 2

4. Version 0.10 (c) 2007 CELEST =R(b) R(b) R(a) E(a) a b E(b) R  E I E(a)/I E(b)/I = E(a) E(b) BRIGHTNESS PERCEPTION IS BASED ON COMPARING TWO SURFACES R(a) R(b) === E(a) I E(b) I x E(a) I E(b) I ÷ The contrast between two surfaces is compared as a ratio of their luminances.

5. Version 0.10 (c) 2007 CELEST MODELS OF BRIGHTNESS CONTRAST PHYSICALSIMILARABSTRACT R(a) R(b) R(b) = E(b) I R(a) = E(a) I BRIGHTNESS CONTRAST REFLECTANCE

6. Version 0.10 (c) 2007 CELEST BRIGHTNESS LAB: AN EXPERIMENT IN PSYCHOPHYSICS Brightness lab will allow you to collect data about your own brightness perception. Psychophysics is the branch of Psychology that deals with the relationship between physical stimuli and mental phenomena. (Oxford American Dictionary)

7. Version 0.10 (c) 2007 CELEST ACCESSING BRIGHTNESS LAB

8. Version 0.10 (c) 2007 CELEST RUNNING BRIGHTNESS LAB

9. Version 0.10 (c) 2007 CELEST OVERVIEW OF BRIGHTNESS LAB

10. Version 0.10 (c) 2007 CELEST INSTRUCTIONS FOR BRIGHTNESS CONTRAST

11. Version 0.10 (c) 2007 CELEST DATA COLLECTION: BRIGHTNESS CONTRAST

12. Version 0.10 (c) 2007 CELEST BRIGHTNESS CONTRAST DATA 