[GRASS5] Driver Update

[Glynn Clements]

Glynn Clements wrote:

> > Any help would be welcome to fix d.his,
> 
> I'll fix this in a similar manner to d.rgb, i.e. scrap the misguided
> attempt to generate a composite "RGB" output layer and just display
> the result of HIS->RGB conversion using R_RGB_raster().

Having looked into this, the name is somewhat misleading:

1. The "hue" map is only really a hue map if used with a colour table
such as "rainbow" where all entries have 100% intensity and
saturation. Otherwise the intensity and saturation values are used to
scale those provided by the i_map and s_map parameters.

2. The "saturation" map isn't. An all-black saturation map would
result in grey-scale output, but specifying an all-black for the
"s_map" parameter will actually output solid 50% grey. "haze map"
would be more accurate.