Imaginary primaries in the CIE color system are used to avoid negative values and are also called what?

In the context of the CIE (Commission Internationale de l'Éclairage) color system, the concept of imaginary primaries helps to maintain a mathematically consistent system for defining colors while avoiding negative values, which can complicate color representation. The correct term for these values is "Tristimulus Values."

Tristimulus Values refer to the three values (often denoted as X, Y, and Z) that are derived from the color matching functions and represent the relative amounts of the three primary colors required to reproduce a given color. In the CIE system, these values allow for the representation of visible colors in a way that aligns with human perception, ensuring that all visible colors can be expressed within the RGB color space without encountering negative values.

This definition underscores the importance of Tristimulus Values in color science and their role as foundational elements in colorimetry, making them distinct from other terms that might relate to color but serve different purposes. For instance, chromatic values and colorimetric values have different focuses, while relative values could imply a comparison rather than a specific representation of color in the tristimulus framework.