Colour

Observations

• Many computer programs provide a colour picker that allows you select a colour by specifing its hue, luminance and saturation. In most cases the scales are chosen for computational convenience and not for perceptual accuracy. An adjustment of one of these qualities usually affects the others. For example, changing the hue will change the luminance. The illustration on this webpage uses improved scales but it remains inaccurate.
• It is intuitively easier to select a colour by adjusting its HLS values than by adjusting its RGB values.
• Use the illustration to make an orange colour. Then, leaving the hue and saturation unchanged, reduce the luminance. Notice that the colour starts to look brown. Brown colours are various kinds of dark orange.
• Use the illustration to make a fairly light, fully saturated yellow. Then, leaving the hue and saturation unchanged, reduce the luminance. Notice that the colour starts to look quite green. Olive green is the name for dark yellow!