Radiation
Goal
Explore the relationship between radiation and appearance.
Experiment
Characterize the appearance of and measure the intensity of the
surface radiation of white, gray, and black targets both under room
light and sun light. (Be sure to make note of angle of the illuminant
source and the viewing angle. Are there specular components?) What do
your results tell you about the relationship between radiation and
appearance?
Equipment
light meter, black, gray, white, and color surfaces
Questions to Consider
- What ways can one describe the stimulation captured by the visual sensors?
- What can isolated stimulation describe and not describe?
- What can stimulation relationships describe and not describe?
- What criteria would a model need to include in its definition to account for appearance?
- Is appearance an object attribute?
- How can one determine if people see the same appearance for the same sensory input?
- Does ``white'' only apply to surfaces?
- Are the conditions that establish white the same for establishing black?
- What guidance is available for conditions in which the sensory stimulus can not be reproduced?
Homework
We theorized that we could predict that relative perceived value could be calculated as follows:
value = (surface reflection / ambient light),
and that contrast could be calculated as follows:
contrast = (light - dark) / (ambient light).
Part 1: Using Java, create a 400x400-pixel applet. You can only use black and white (no Java gray). Create a graphical object that appears gray. The interface should be simple, click once and the object should appear light, click again and the object should appear dark. You can do this through any means except changing the color of the object itself. Try to be creative. The conditions you implement could involve size, texture, motion, etc... It is more important to experiment than to present a foolproof solution.
Part 2: Given that these theories are true, what would you speculate
about noise sensitivity as a function of lighting conditions?
Part 3: A television with the power off appears to be a greenish-gray
color . Explaination how you perceive black on television when the set
is turned on?
Suggested Reading
- Evans, pp. 125-129, 157-171
- Hardin, pp. 24-25, 83
- Raster Graphics Handbook, pp. 14-25
Last Modified: November 08, 1997