Trouble with dump_region, plane_groups

[Daniel A Staver]

I have a problem getting a proper dump of a region on the screen when the
region of interest has pixels in both the color and b/w planes.

What I would like is to generate a color raster file which would contain
pixel information from both planes as selected by the enable plane. If any
of the pixels are from the b/w plane, then just select those for merging
into the color-plane raster dump.

How does one dump the enable plane? Can there be more than 256 colors such
that I can have 256 colors for my color-plane and also have 2 extra for
black and white, or do I need to find the "lightest" and "darkest" out of
the 256 available colors in the current color map (selected by my
application program - IDL) and map the b/w pixels to these two colors?
The normal programs, dumpregion, screendump, etc, only get from one device
(display buffer) it seems.