Declaration: Frm2DImg.SetDisplayMode(ImgHandle: integer; Mode: integer): integer;
Sets the display mode of the image referenced by the handle ImgHandle. The image handle has a valid range of 0 to 16. The handle 0 refers to the main image of the 2D Imager, the handles 1 to 16 refer to the special images (if available). The parameter Mode may take the following values:
0 ... monochrome isohypses
1 ... colored isohypses
2 ... colored interpolated surface,
3 ... colored surface, not interpolated (pixel resolution)
The function returns the following error codes:
 0 ... everything OK
-1 ... the image handle is invalid or points to a non-existing image
-2 ... the mode is invalid