Patent ID: 7009734
Filing Date: 2006-03-07
Classification: H04N

Abstract:
1. A method of forming a color transform lookup table comprising: a step of forming a first table describing the correspondence between representative points in an input color space and output signal values when transition is from white to black; a step of forming a second table describing the correspondence between representative points in an input color space and output signal values when transition is from white to a first primary color; a step of forming a third table describing the correspondence between representative points in an input color space and output signal values when transition is from the first primary color to black; a first interpolation step of forming a triangular plane OPQ which has black, white, and the first primary color as apexes O, P, and Q, respectively, which represents a color space, and in which the first table corresponds to an axis PO, the second table corresponds to an axis PQ, and the third table corresponds to an axis OQ, and interpolating output signal values at lattice points when the triangular plane OPQ is divided into a lattice structure; and a first replacement step of dividing the triangular plane OPQ into regions by using, as a boundary, a line AB connecting a lattice point A, on the axis PO, which is before black output signal value>0 in the transition from P to O and a lattice point B, on the axis QO, which is before black output signal value>0 in the transition from Q to O, and replacing the interpolated black output signal value with 0 and the output signal value of a complementary color corresponding to the primary color with a predetermined signal value, at individual lattice points in a region in the direction of the axis PQ.