PRO EXAMPLE steps = 100 scaleFactor = FINDGEN(steps) / (steps - 1) ; Do first 100 colors (yellow to blue). ; Red vector: 255 -> 0 redVector = 255 + (0 - 255) * scaleFactor ; Green vector: 255 -> 0 greenVector = 255 + (0 - 255) * scaleFactor ; Blue vector: 0 -> 255 blueVector = 0 + (255 - 0) * scaleFactor ; Do second 100 colors (blue to red). ; Red vector: 0 -> 255 redVector = [redVector, 0 + (255 - 0) * scaleFactor] ; Green vector: 0 -> 0 greenVector = [greenVector, REPLICATE(0, steps)] ; Blue vector: 255 -> 0 blueVector = [blueVector, 255 + (0 - 255) * scaleFactor] TVLCT, redVector, greenVector, blueVector image = FINDGEN(200) # REPLICATE(1, 40) WINDOW, XSIZE=200, YSIZE=40 TV, BYTE(image) END