Hello my name is Jonathan I'm a french student (So sorry for my english) I work in an Hospital with IDL on a software : PERFTOOL And I've got a problem : I am obliged to launch the computer 256 colors to see curves. In 16 million colors the curves do not appear. It must be a problem with the graphic panel. This is the code of the graphic panel : IF (!D.N_COLORS GT 256) THEN BEGIN PRINT, 'Too many colors ('+ CLEAN(!D.N_COLORS) + ' NUM_COLORS = 256 ENDIF ELSE NUM_COLORS = !D.N_COLORS F = FINDGEN(NUM_COLORS - STATIC_COL) * 255./FLOAT(NUM_COLORS-STATIC_COL-1) R = BYTARR(NUM_COLORS) G = BYTARR(NUM_COLORS) B = BYTARR(NUM_COLORS) R(STATIC_COL:*) = F+0.5 G(STATIC_COL:*) = F+0.5 B(STATIC_COL:*) = F+0.5 R(0) = 0 & G(0) = 0 & B(0) = 0 ; black R(1) = 50 & G(1) = 0 & B(1) = 100 ; purple R(2) = 0 & G(2) = 90 & B(2) = 255 ; dark blue R(3) = 0 & G(3) = 150 & B(3) = 255 ; blue R(4) = 0 & G(4) = 255 & B(4) = 255 ; cyan R(5) = 0 & G(5) = 150 & B(5) = 0 ; green R(6) = 100 & G(6) = 255 & B(6) = 0 ; yellow-green R(7) = 255 & G(7) = 255 & B(7) = 0 ; yellow R(8) = 255 & G(8) = 85 & B(8) = 0 ; orange R(9) = 255 & G(9) = 0 & B(9) = 0 ; red R(10) = 255 & G(10) = 255 & B(10) = 255 ; white TVLCT, R, G, B R = 0B & G = 0B & B = 0B & F = 0B END