HLS color model A color model that defines colors by the three parameters hue (H), lightness (L), and saturation (S). It was introduced by Tektronix Inc. Hue lies on a circle, saturation increases from center to edge of this circle, lightness goes from black to white. This model uses the same hue plane as the HSV model, but it replaces value (V) by an extended lightness axis so that the maximum color gamut is at L=0.5 and decreases in each direction towards white (L=1) and black (L=0). The HLS color model is represented by a double hexagonal cone, with white at the top apex and black at the bottom.
HLS Color Model This model, Hue, Lightness, and Saturation, was popularized by Tektronix who used it to define the color effects on its monitors. It uses a double cone, as shown below:
The hues are specifies by angles, as they were for HSV, but in this model Blue is at 0°, Magenta is at 60°, Red is at 120°, Yellow is at 180°, Green is at 240°, and Cyan is at 300°. So the order on which the colors appear is the same as before, and complementary colors are still on opposite sides of the circle, separated by 180°, but the color sequence begins with blue instead of red. The angle is measured from above, as before, beginning at the line shown from medium gray to blue. The hue definitions now lie on a circle, as compared to the hexagon that was used for HSV. This is much easier to deal with since full saturation of any hue will now have an S value of 1.0, as compared to, for example, the 2 3 that we had to use for the S value for orange using HSV. Once again, gray scales appear on the center line of symmetry, with L = 0 at the bottom and L = 1 at the top. In this model the line is twice as long as in HSV.
Pure colors have an L value of 0.5. So, for example, pure orange is at an HLS triple of (150°, 0.5, 1.0). Overall HSV seems to be the preferred method for interactive selection of colors.