The color wheel is a two-dimensional circular color arrangement used in various color models to represent color saturation and hue. The center of the color circle represents achromatic colors, and color saturation is represented by the length of the color vector from the center to the outer edge.
Short color vectors denote less saturated colors, long color vectors denote saturated colors. The maximum color saturation is formed by a long color vector, which corresponds to the radius of the color circle and thus has the greatest possible length. The hue is determined by the angle of the color vector. By definition, the color vector angle of 0° corresponds to red (R), 120° corresponds to green (G), and 240° corresponds to blue (B). R, G and B are the primary colors for additive color mixing. Between R, G and B are the primary colors for subtractive color mixing. Yellow (Y) has a color angle of 60°, cyan (C) one of 180° and magenta (M) one of 300°. The colors opposite each other in the color wheel are the complementary colors, they are offset by 180° with respect to the primary colors.
In the PAL television standard, the PAL- RGB color wheel is used. As with the other color circles, the color saturation is expressed in the length of the color vector, the hue in the angle. The center of the color circle is achromatic. As axes one uses the color difference signals reduced in level, the U and V signal. The angle of the color vector is calculated by the tangent from the individual color components. The vectorial representation plays an important role in television measurement technology and is displayed on a vectorscope.