Sabrina Color Models
Sabrina works with a snall number of basic colors, such as green, red,
blue, etc., and a a number of shades, or intentsities, of these colors.
The color of a pixel in a ray-traced rendering is determined by the
color assigned to the cell that the ray intersects. The shade of
that color depends on the angle the ray makes with the surface.
The intensity darkens as the angle increases.
Sabrina recognizes the color capability of the display, from 2 bit
monochrome to 24 bit TrueColor.
Monochrome (2 colors) Displays
Only Etch images and Line Drawings are allowed; Color ray tracing
is not permitted.
PseudoColor(16 to 226 Colors) Displays
Sabrina createsa color map using as many shades of each (8 or 4) basic
color as can be accomodated by the total number of colors available.
The user can control the size of the color map.
Sabrina color palette for an 8 Plane PseudoColor display.
HighColor (>256 Colors) to TrueColor (24 bit or more) Displays
Sabrina assumes the system will faithfully represent each requested
color. The exact color of each pixel is specified.
Sabrina color palette for
a TrueColor display.
Comparison of Color Models
Distinct shading bands may be visible on curved surfaces in
the PseudoColor model, especially when a large number of basic
colors are used. Consider the
8 plane PseudoColor and TrueColor
images of the superconducting supercollider particle detector.
PseudoColor images without shading bands
may result from defining only a
few (2 or 3) basic colors.
Default Basic Colors
The basic colors defined by default depends on the number of color planes
(or, equivalently, the number of colors = 2planes).
An 'X' in the table means the basic color is defined. The Red-Green-Blue
components range from 0 (off) to 1 (full intensity).
| Color Planes |
|---|
| Color | Red | Green | Blue | 4 | 6 | 8 | > 8 |
|---|
| White | 1 | 1 | 1 | X | X | X | X |
| Red | 1 | 0 | 0 | X | X | X | X |
| Green | 0 | 1 | 0 | X | X | X | X |
| Purple | 0 | 1 | 1 | X | X | X | X |
| Blue | 0 | 0 | 1 | | X | X | X |
| Magenta | 1 | 0 | 1 | | X | X | X |
| Yellow | 1 | 1 | 0 | | X | X | X |
| Black | 0 | 0 | 0 | | X | X | X |
| Brown | 0.7 | 0.5 | 0.3 | | | | X |
| Orange | 1 | 0.6 | 0 | | | | X |
| Pink | 1 | 0.8 | 0.8 | | | | X |
| LightRed | 1 | 0.6 | 0.6 | | | | X |
| Gray | 0.7 | 0.7 | 0.7 | | | | X |
| DarkGray | 0.5 | 0.5 | 0.5 | | | | X |
| DrkGreen | 0 | 0.75 | 0 | | | | X |
| Violet | 0.8 | 0 | 1 | | | | X |
Last modified: September, 2004
Kenneth A. Van Riper /
email
