Patent ID: 7167276

Claim:
Method of converting a color data value (a, b) from rectangular color coordinates to a corresponding color data value (C, h) in polar coordinates comprising: calculating a ratio γ based on the absolute value of the ratio of b and a; accessing a first one-dimensional look-up table implementing the values (√{square root over (1+γ 2 )}) on the range of [0 to 1] to obtain a first look-up value; resolving the diagonal quadrant for C based on the ratio γ; calculating C based on the resolved diagonal quadrant and the first look-up value; accessing a second one-dimensional look-up table implementing the values arctan (γ) on the range [0 to 1] to obtain a second look-up value; resolving the octant for h based on the values of a and b and based on the ratio γ of a and b; and calculating h based on the resolved octant and the second look-up value.