HSL Color Model
The definition of the HSL model is given below.
- Saturation indicates the purity of a color. Highly saturated colors are vivid, while desaturated colors are dull or “dirty”. Saturation characterizes colorfulness relative to a neutral gray of the same brightness. It is represented by the distance from the center of the color wheel (see below).
- Lightness of a color is a description of the amount of light reflected or transmitted. It is defined as the colors brightness relative to a white. Lightness is achromatic, i.e. it contains no information about the color of an object, only how light or dark it is.
- Each attribute (coordinate) of the HSL color model is independent of the others. (see depiction below).
HSB Color Model
The HSB color model is similar to the HSL model. However, it is based on the RGB intensities of the display colors.
- The hue of a color is adjusted by altering the balance of RGB intensities, keeping the total intensity the same.
- The saturation of a color is adjusted by adjusting the intensities of the complimentary RGB colors keeping the dominant color the same.
- The brightness of a color is adjusted by scaling the RGB intensities equally, keeping their ratios the same.
- HSB is supported by many software applications including Photoshop and the color picker in MacOS. A feeling for HSB can be obtained by entering several selected values of RGB or HSB in the color picker in Photoshop. (Ignore the discussion of the dependence of saturation and brightness on one another in the book as it doesn’t reflect the behavior of the color picker in Photoshop 4.0 and beyond). We illustrate in Photoshop.