NAME:		harwell colormap

AUTHOR INFO:	Kevin White, Stardent Computer Ltd., 011-44-483-505388

SOURCE FILE:	hwell.c

TYPE:		data

INPUTS:		NONE

OUTPUTS:	colormap

PARAMETERS:     Name		Type	Default		Min	Max 
		Gamma		float	 1.4		0.	5.
		blue c/o	float	 0.3		0.	1.
		green c/o	float	 0.45		0.	1.
		red c/o		float	 0.67		0.	1.
		Range Mode	choice   continuous     continuous/stair-step
		No. of Steps	int	 16		2	64

DESCRIPTION:
	Harwell is a special color map generator. It provides a standard
fringe color set, based on a transfer equation. It is gamma corrected,
and has essentially three regions, with linear interpolation between
the regions. The regions are

   blue --> green --> yellow --> red

The cutoff points are controlled by the three float dial parameters.
The gamma is also adjustable. The default values are designed
for the "standard fringe".

This module can be used anywhere "generate colormap" can be used.

As it does not have an interactive color window widget, you can
see the colormap using "display colormap" from the user
contributed library, or "field legend" in AVS3.

An optional mode creates a "stair step" color map, with integer
step transitions between color regions. The steps are uniform,
but the color assignments still use the analytic transfer function.
The number of steps are controlled by the No. of Steps dial.

The choice selector switches between continous smooth fringe ramp,
and the stair step mode.
In stair-step mode, the 1st entry will be blue, and to last red.
For only 2 steps, these are the only colours, with the break point
in the center of the colormap.

Strange results will result if the color cutoff points are set
non-monotionic. For instance if the blue c/o is at a higher value
than the green c/o, a discontinuity will result. There is no 
bug here, If you like what you see, go ahead and use it!