> one cannot choose colors which have the desired brightnesses and hues providing that it is within the range of colors that a monitor can display? No, the pro

> one cannot choose colors which have the desired brightnesses and hues providing that it is within the range of colors that a monitor can display? No, the problem is that you can't choose colors which have the desired brightnesses, hues, and saturation. If you start with a ideal #00F blue and try to make it lighter, you have to add red and green, which reduces the saturation. Conversely, if you start with a ideal #FF0 yellow and try to make it darker, you have to remove red and green, which also[0] reduces saturation. For most colors this reduction in saturation isn't too bad, but for dark yellow it produces a ugly (if you wanted yellow) shade of brown, and for light blue it produces a very washed out shade of blue (also ugly if you wanted a proper blue). > a 16-color version of this palette [...] have the same apparent brightness as each other TFA's palette doesn't have the same apparent brightness, and cites this problem specifically for why: > > An HSL rainbow colour palette can be created by choosing fixed chroma and luminance values and varying the hue. However, the resulting palette looks unpleasant because yellow is darkened to brown, red is lightened to pink, and blue becomes very pale. (You can fudge the red in practice (IME), but getting a properly saturated bright blue would require more photons than a white (fully-on) pixel has.) Edit: 0: Well, saturation in the sense of distance-from-same-brightness-gray - depending on your color model, you might define saturation as angle from gray in color-vector-space, in which case dark yellow doesn't count since it's a scaled-down version of regular yellow. Not sure offhand which sense is more common, but GIMP at least seems to use angle, so feel free to suggest less-ambiguous terminology if you've got it.