Color solid
); or the 2D chromaticity diagram (also known as color triangle), which depicts the variables of hue and spectral purity.
Many are in the shape of a sphere, whereas others are warped three-dimensional ellipsoid figures—these variations being designed to express some aspect of the relationship of the colors more clearly.
The vertical axis of the color solid, then, is gray all along its length, varying from black at the bottom to white at the top, it is a grayscale.
[4] For now, we are unable to produce objects with such colors, at least not without recurring to more complex physical phenomena.
With the current state of technology, we are unable to produce any material or pigment with these properties.
In optimal color solids, the colors of the visible spectrum are theoretically black, because their reflectance spectrum is 1 (100%) in only one wavelength, and 0 in all of the other infinite visible wavelengths that there are, meaning that they have a lightness of 0 with respect to white, and will also have 0 chroma, but, of course, 100% of spectral purity.
[6] In linear color spaces that contain all colors visible by humans, such as LMS or CIE 1931 XYZ, the set of half-lines that start at the origin (black, (0, 0, 0)) and pass through all the points that represent the colors of the visible spectrum, and the portion of a plane that passes through the violet half-line and the red half-line (both ends of the visible spectrum), generate the "spectrum cone".
If it is expanded even more, it will cover more wavelengths than the yellow semichrome does, approaching white, until it is reached when the full spectrum is reflected.
They were called semichromes or full colors by the German chemist and philosopher Wilhelm Ostwald in the early 20th century.
The idea of optimal colors was introduced by the Baltic German chemist Wilhelm Ostwald.
On modern computers, it is possible to calculate an optimal color solid with great precision in seconds.
Artists and art critics find the color solid to be a useful means of organizing the three variables of color—hue, lightness (or value), and saturation (or chroma), as modelled in the HCL and HSL color models—in a single schematic, using it as an aid in the composition and analysis of visual art.
