I did a screen capture of an image and displayed it on the SLCD6 or SLCD43 (in high color mode) and see color banding that was not in the original. What do I do to get rid of this?

Natural images (pictures) display quite well using 16-bit color. However, some computer-generated artwork images contain continuously varying color gradients that look banded when converted to 16-bit color. To resolve this, use error diffusion (dithering) to smooth out the banding. Look in the GIMP documentation or glossary for information on dithering support.