The iris4d driver can operate in two modes.
Syntax:
set terminal iris4d {24}
If the hardware supports only 8 bits, use the default set terminal iris4d. If, however, the hardware supports 24 bits (8 per red/green/blue), use set terminal iris4d 24.
When using 24-bit mode, the colors can be directly specified via the file .gnuplot_iris4d that is searched in the current directory and then in the home directory specified by the HOME environment variable. This file holds RGB values for the background, border, labels and nine plotting colors, in that order. For example, here is a file containing the default colors:
85 85 85 /* Back Ground */
0 0 0 /* Boundary */
170 0 170 /* Labeling */
85 255 255 /* Plot Color 1 */
170 0 0 /* Plot Color 2 */
0 170 0 /* Plot Color 3 */
255 85 255 /* Plot Color 4 */
255 255 85 /* Plot Color 5 */
255 85 85 /* Plot Color 6 */
85 255 85 /* Plot Color 7 */
0 170 170 /* Plot Color 8 */
170 170 0 /* Plot Color 9 */
This file has exactly 12 lines of RGB triples. No empty lines are allowed and anything after the third number in line is ignored.