function color24, r, g, b ;+ ; NAME: ; COLOR24 ; ; PURPOSE: ; Return the 24-bit color index for an RGB triplet. ; ; CALLING SEQUENCE: ; RESULT = COLOR24(R, G, B) ; ; INPUTS: ; R - 8-bit red color index. ; G - 8-bit green color index. ; B - 8-bit blue color index. ; ; KEYWORD PARAMETERS: ; None. ; ; OUTPUTS: ; RESULT - the 24-bit color index for the RGB triplet. ; ; COMMON BLOCKS: ; None. ; ; EXAMPLE: ; Return the 24-bit color index for pure green: ; ; IDL> print, color24(0,255,0) ; ; MODIFICATION HISTORY: ; 02 Mar 2003 Written by Tim Robishaw, Berkeley ;- if (N_params() lt 3) $ then message, 'Syntax: RESULT = COLOR24(r,g,b)' ; DO THE R, G, B VECTORS HAVE THE SAME SIZE... if not( (N_elements(r) eq N_elements(g)) AND $ (N_elements(r) eq N_elements(b))) $ then message, 'r, g, and b vectors must have same size.', /INFO ; RETURN THE 24-BIT COLOR INDEX FOR AN RGB TRIPLET... return, long(r) + ishft(long(g),8) + ishft(long(b),16) end; color24