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The default behaviour of PS is to always present color in terms of its RGB values. RGB values are fine for when we are color correcting but when we are picking color, or when we are thinking about the pictorial aspects of an image, HSB is best. HSB stands for Hue, Saturation and Brightness.

Below is a pictogram of HSL values. Note how both Lightness and Saturation are 'ramp' values: beginning at zero and ending at one. Hue, on the other hand, is best understood as values round a wheel. Lightness is easy to understand and relatively easy to organise. Hue is the 'name' of the color (red, blue, orange etc) and is sometimes also called the hue term. Saturation can be understood as indication the 'presence of perceptually apparent hue', hence grey, white and black present zero saturation and a sunflower presents full saturation.

HSL 02.png

Here are the HSL values of a Monet painting presented as channels. Note how in this particular painting the saturation value is what drives the presence of the sun (note also the awful noise in the hue channel, a feature common to most digitally acquired image).

HSL 01.jpg

Though your changes will be to the RGB values of an image, when color correcting an image it is the H, S and B that should be separately considered... usually in the order B, S then H. The same applies when stylizing an image.

My lecture notes on color (i.e. hue and saturation) are here: Color_forPS_s.pdf (right click download)

My lecture notes on tone (i.e. lightness) are here: Tone_s.pdf (right click download)