Extensible multi‐primary control sequences

— In a display with more than three primaries (called a multi‐primary display), a color can be expressed as multiple combinations (called control sequences) of primaries. This paper presents an algorithm for assigning control sequences that preserves current assignments when further primaries are added. These control sequences are cal led extensible. It is shown that the gamut of any number of primaries is a zonohedron, which can be dissected into parallelepipeds. Control sequences are assigned within each parallelepiped. The current parallelepipeds remain when more primaries are added, so the current assignments are preserved. Multi‐primary displays can also cause unwanted metamerism and make continuous color scales appear discontinuous. The algorithm avoids these problems. When viewed through natural filters, such as yellowed ocular lenses, multi‐primary displays can sometimes make two different colors appear identical. If the primaries satisfy the Binet—Cauchy criterion, which is always the case when all primaries are monochromatic, then these spurious matches are avoided.