Editing Color (section)

=== Maximum chroma colors, semichromes, or full colors ===
Each hue has a maximum chroma point, semichrome, or full color; objects cannot have a color of that hue with a higher chroma. They are the most chromatic, vibrant colors that objects can have. They were called '''semichromes''' or '''full colors''' by the German chemist and philosopher [[Wilhelm Ostwald]] in the early 20th century.<ref name="thi"/><ref name="Ost">{{cite journal |last1=Liberini |first1=Simone |last2=Rizzi |first2=Alessandro |year=2023 |title=Munsell and Ostwald colour spaces: A comparison in the field of hair colouring |url=https://onlinelibrary.wiley.com/doi/10.1002/col.22818|journal=Color Research and Application|volume=48 |pages=6–20 |doi=10.1002/col.22818 |hdl=2434/940227 |hdl-access=free }}</ref>

If B is the complementary wavelength of wavelength A, then the straight line that connects A and B passes through the achromatic axis in a linear color space, such as LMS or CIE 1931 XYZ. If the reflectance spectrum of a color is 1 (100%) for all the wavelengths between A and B, and 0 for all the wavelengths of the other [[half]] of the color space, then that color is a maximum chroma color, semichrome, or full color (this is the explanation to why they were called '''semi'''chromes). Thus, maximum chroma colors are a type of optimal color.<ref name="thi"/><ref name="Ost"/>

As explained, full colors are far from being monochromatic (physically, not perceptually). If the spectral purity of a semichrome is increased, its [[colorfulness|chroma]] decreases, because it will approach the visible spectrum, ergo, it will approach black.<ref name="thi"/>

In perceptually uniform color spaces, the lightness of the full colors varies from around 30% in the violetish blue hues, to around 90% in the [[yellow]]ish hues. The chroma of each maximum chroma point also varies depending on the hue; in optimal color solids plotted in perceptually uniform color spaces, semichromes like red, green, violet, and [[magenta]] have a high chroma, while semichromes like yellow, orange, and [[cyan]] have a slightly lower chroma.

[[File:Munsell 5 PB 5Y.png|thumb|Slice of the Munsell color space in the hues of 5PB and 5Y. The point farthest from the achromatic axis in each of these two hue slices is the maximum chroma color, semichrome, or full color of that hue|200x200px]]