Explanation
Hue may be described as the underlying colour of a colour.
A red and a pink may have the same hue (the pink having a higher luminance);
a yellow and a brown may have the same hue
(the brown having a lower saturation
and a lower luminance);
a red and an orange, however, must have different hues because they are essentially different colours.
In many cases the name of a colour is based on the name of its hue—green,
light yellow, deep purple, bright orange, a washed-out blue and so on.
(Green, yellow, purple, orange and blue describe the hues.)
Some observations
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The full range of hues comprises all the spectral colours
and a range of purple and magenta hues that do not appear in the visible spectrum.
The easiest way to visualise this is to arrange the hues around a
colour wheel
with the spectral hues arranged most of the way round, starting with red,
and with the purple-magenta range completing the circle from violet back to red.
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Many computer programs will describe a hue by the angle between it and red on the colour wheel.
For this reason the easiest way to program the slider was to make it
show the same hue at the top and bottom of the scale.
