Problem: HPGL2/RTL: shades plotted with wrong color for maps containing images
Solution or Workaround
Shades print out blank or with the wrong color when using HPGL2 or RTL on a .gra file containing an image, even if the Static Colors option is set to 0.
HPGL2 can plot only 256 colors at any one time. A color image will use many of these colors; thus, subsequent polygons will be plotted with the nearest available color. Lighter shades will often plot as white, other shades may plot in slightly different colors.
While creating the .gra file, be mindful of the number of colors and the order of the objects. If the colors used exceed 256, place the vector objects first, then the image. Run HPGL2 and RTL with static colors set to 0. This will allow the vector objects to have their proper colors assigned, and the image will still plot OK.
If you have access to ArcPress, you should use PostScript. PostScript has 16.7 million available colors and so you will never have color mismatching problems.