  A three-polar, cf. T. Gregor, J. Halu\v{s}ka, Lexicographical ordering and
field operations in the complex plane. Stud. Mat. 41(2014), 123--133.,
$HSV-RGB$ Colour space $\triangle$ was introduced and studied. It was equipped
with operations of addition, subtraction, multiplication, and (partially)
division. Achromatic Grey Hues form an ideal $\mathfrak{S}$. Factorizing
$\triangle$ by the ideal $\mathfrak{S}$, we obtain a field $\triangle |
\mathfrak{S}$. An element (i.e an individual Colour) in $\triangle |
\mathfrak{S}$ is a triplet of three triangular coefficients. The set of all
triangular coefficients is a subset of a semi-field of parabolic-complex
functions. For the parabolic-complex number set, cf.~A. A. Harkin--J. B.
Harkin, Geometry of general complex numbers. Mathematics magazine, 77(2004),
118--129.
