Hue - Saturation - Luminance

Most applications allow picking colour either by RGB (red, green, blue) values or HSL (hue, saturation and luminance). The ways of scaling can vary between applications - Paint Shop Pro uses 0 to 255 for all three qualities, Photoshop has an HSL plug-in, but uses HSB (brightness) in its colour picker. Hue is expressed in the degree around the colour wheel, while saturation and brightness are set as a percentage. Shade uses a standard Windows colour picker with a scale of 0 to 239 (which can be regarded as 1 to 240) for each quality, which makes calculations easy.

The colour picker from Shade with Cyan chosen.


Hue is best seen as a colour wheel with red at 0 and 240, though the wheel only goes to 239. Thus the primary colours Red, Green and Blue are all 80 apart, and the secondary colours, Yellow, Cyan and Magenta spaced in between them. This gives us six easy to remember points of reference. From this if you say "Gold", I think hue 30. If you say "Orange" I think hue 20. Skin tones tend to be around a value of 10, though they do vary depending upon complexion.

If I have ten objects or ten lights and I want to cover the spectrum with each colour an equal distance from those on each side, I use a series based on steps of 24. (240/10=24) This works very well with lights, adding up to white light wherever the distances are equal. It also guarantees that the no colour will predominate. This works for any number of lights or objects less than 120 in total.

Click to see relatedpractical examples of how this works in Shade.


This illustrates the effect of saturation. At 239, colours are as saturated as possible - and a zero, they are all neutral grey.


Luminance is the lightness or brightness of a chosen colour. Pure black at zero, no matter what hue or saturation is set, and white at 239.

Hue, saturation and luminance is a very good way to approach colour. Once understood, exactly the desired colour and shade can be quickly found and fine tuned through Shade's Surface palette and colour picker.

The basic colour of any object is set with Diffuse and the amount can be varied either by typing a number between 0 and 1.0 or moving the slider and watching the example. Clicking on the rectangle to the right of any slider will bring up the colour picker shown at the top of this page. The effect is previewed on the sphere in hte preview window.

While the example at left is somewhat absurd, it does illustrate how complex colouring a surface can be, The Surface palette is an extremely powerful feature in Shade.

©2007 Larry N.Bolch