Graded by: Toli Lerios
The following questions concen the representation of color used in computer
A. (10 points) Briefly, what do the terms hue, saturation, and value
Hue: The "intrinsic color", or the dominant wavelength.
Saturation: The "purity", or how "washed out" a color is, or how much/far the
color/dominant wavelength is from a gray of same value.
Value: The "brightness" or "intensity", how dark the color is, how close to
black the color is.
B. (10 points) When drawing a polygon, colors at vertices are often
interpolated so that the colors in the interior of the polygon are smoothly
graded across the polygon. Is it better to interpolate the colors in an RGB
coordinate system, or a HSV coordinate system. Explain your reasoning.
- Linearly interpolating R,G,B values moves result along a line
joining endpoints (ie. colors at vertices). RGB is a linear, additive color
- RGB accurately represents mixing of lights (linear, additive space), and
lit-to-shadow transtitions. Shading has to take place in RGB.
- No need to convert for display since framebuffers are RGB.
- HSV interpolation yields psychadelic colors when interpolated hues are
far apart (Try it).
Copyright © 1996 Pat Hanrahan