Is the color at each Copunctal point real or imaginary in the CIE diagram?

The color at each Copunctal point in the CIE diagram is considered imaginary. This notion comes from the fact that the CIE diagram is a representation of colors that can be perceived within the limits of human vision, and the points within this diagram represent colors that can be produced by the additive mixing of primary colors (red, green, and blue). However, not all points within the diagram correspond to colors that can be produced by real physical mixtures of light; some represent colors that are outside the gamut of what can be observed in real life.

Imaginary colors are those that arise based on mathematical models of color representation rather than colors that can be directly produced or seen in typical human vision. Therefore, while all points in the CIE diagram pertain to colors perceived by the human visual system, the concept of Copunctal points encompasses those colors that can exist in theory but do not have a physical counterpart in an additive color system. This understanding is crucial for applications in color science and visual perception studies, where the distinction between real and imaginary colors helps clarify the limitations of color representation.