Hi Jan,
> Does anybody know any resources where these systems are explained
> (preferably with some conversion algorithms)?
Foley and Van Dam's "Computer Graphics: Principles and Practice"
describes a lot of the terms and protocols we use in the 2D API.
In particular, they define the HSV (aka HSB) conversion algorithm
that we use under the name HSB. HSV stands for Hue, Saturation,
and Value and HSB stands for Hue, Saturation, and Brightness.
Value and Brightness are the same measurement, but Brightness is
a more colloquial term for it.
> Red = 128, Green = 80, Blue = 64
> Java-HSB: 0.41667, 0.5, 0.50196
> PSP-HSB: 11, 85, 96
If you look in the Foley and vanDam reference there is another
algorithm described there called HLS which stands for Hue, Lightness
and Saturation. That algorithm produces numbers nearly identical
to the PSP's numbers except in a different order (PSP looks like it
is returning H, S, L in that order) and with a different scale
for the Hue (FvD use 0-360 whereas PSP seems to use 0-255).
HSV/HSB produce values in a space that is a single "cone" with a
hexagon at its top and a point at its bottom. Any color that
has at least 1 RGB parameter of 255 will be mapped onto the
hexagon face of that "cone" with white in the center and pure
colors (R,G,B,Y,M,C) at the vertices of the hexagon. Black is
at the point at the bottom.
HLS produces values that map into two such cones stuck together
at their hexagon bases. White is the point at the top. Black is
the point at the bottom. Pure colors are at the vertices of the
hexagon in the middle.
FvD gives better descriptions of the why and wherefores of the
two algorithms as well as pretty pictures of the cones they map
into.
Does that help?
...jim
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