pixel information

Hi List,

There are CAM programs which turn graphics (bitmap etc) into
toolpaths converting color to z-depth, etc.

If we have a digital image, how do we extract the color information
(hue, saturation, brightness...) from it?

To clarify further: For example, we have a greyscale map of USA with
each State coloured a different shade of grey. Is there a way (with
Photoshop, Wintopo, or other program) we can press a button so that
the State with the color (eg brightness) value of 50 (or between 48
and 52) will be isolated (or highlighted)? Or if we placed a cursor
over the area (pixel) and a pop-up balloon gives information on the
color value of that area (pixel)

Thanks

Peter