Mapping RGB Triples Onto 16 Distinct Value
| code | red | G | B |
| 0 | 0 | 0 | 0 |
| 1 | 0.5 | 0.5 | 0 |
| 2 | 0.5 | 0 | .5 |
| 3 | 1 | 0 | 0 |
| 4 | 0 | 0.5 | .5 |
| 5 | 0 | 1 | 0 |
| 6 | 0 | 0 | 1 |
| 7 | 0.33 | 0.33 | .33 |
| 8 | 0.66 | 0.66 | .66 |
| 9 | 1 | 1 | 0 |
| 10 | 1 | 0 | 1 |
| 11 | 1 | 0.5 | .5 |
| 12 | 0 | 1 | 1 |
| 13 | .5 | 1 | .5 |
| 14 | .5 | 0.5 | 1 |
| 15 | 1 | 1 | 1 |
from graphics gems II
struct rgb_color cc[] = { { 1 , 0 , 0 }, { 1 , 1 , 0 }, { 0 , 1 , 1 }, { 0 , 0 , 1 }, };
algorithm to fill in colormap
- subdivide
| base pos | colormap pos | index |
| 0 | 0 | |
| 1 | 19.75 | |
| 2 | 39.5 | |
| 3 | 79 |
given an index, find the range and interpolate