The GAMMA_CT procedure applies gamma correction to a color table.
This routine is written in the IDL language. Its source code can be found in the file gamma_ct.pro in the lib subdirectory of the IDL distribution.
GAMMA_CT, Gamma [, /CURRENT] [, /INTENSITY]
The value of gamma correction. A value of 1.0 indicates a linear ramp (i.e., no gamma correction). Higher values of Gamma give more contrast. Values less than 1.0 yield lower contrast.
Set this keyword to apply correction from the “current” color table (i.e., the values R_CURR, G_CURR, and B_CURR in the COLORS common block). Otherwise, correction is applied from the “original” color table (i.e., the values R_ORIG, G_ORIG, and B_ORIG in the COLORS common block). The gamma corrected color table is always saved in the “current” table (R_CURR, G_CURR, B_CURR) and the new table is loaded.
Set this keyword to correct the individual intensities of each color in the colortable. Otherwise, the colors are shifted according to the gamma function.