Outlines of a Theory of Photopic Colorimetry (Part II) Basic Colorimetry or Affine Color Properties, Continued (First Article)

Abstract

A formal system of human color perception has been described, which is known as basic colorimetry. Positions of the associated color space represent spectral colors, purples, and the color white – among others. Actual colors in color space form at least a three-dimensional color envelope. This chapter describes some affine-invariant properties of the color envelope. The role which plane projective geometry plays in the subordinate color plane is the same as the role which affine geometry plays in color space. The derivation of color coordinates is demonstrated for an arbitrary function of wavelength, as is the derivation of color coordinates under affine transformation of color space. A relation is established between the color matches which are made by dichromat observers, and color matches made by trichromats (color-normal observers). Basic colorimetry provides the foundation for advanced colorimetry as developed in a subsequent chapter.