Patent ID: 8237747

Claim:
A method of converting a three primary color input signal (Cx, Cy, Cz) into N drive signals (P 1 , . . . , PN) for driving N>3 primary colors of a multi-primary color display, the display comprising a plurality of pixels with each pixel comprising N sub-pixels and each of the respective N drive signals (P 1 , . . . , PN) supplied for driving a respective sub-pixel, the method comprises: determining, via a range circuit, a common range (VS) wherein the N drive signals (P 1 , . . . , PN) all have valid values in a coordinate system defined by a minimum and maximum drive range and the N−3 drive signal(s) by performing the steps of (i) defining, via the range circuit, three functions representing three of the drive signals (P 1 , P 2 , P 3 ) wherein each of the three functions is a function of the remaining N−3 drive signal(s) (P 4 , . . . , PN), (ii) calculating, via the range circuit, the common range (VS) for the N−3 drive signal(s) in a space formed by the N−3 drive signal(s) (P 4 , . . . , PN) wherein each one of the three functions representing three of the drive signals (P 1 , P 2 , P 3 ) has valid values in the coordinate system, and (iii) calculating, via the range circuit, border values for the common range (VS), wherein the three functions are defined by [ P ⁢ ⁢ 1 P ⁢ ⁢ 2 P ⁢ ⁢ 3 ] = [ P ⁢ ⁢ 1 ′ P ⁢ ⁢ 2 ′ P ⁢ ⁢ 3 ′ ] + [ k ⁢ ⁢ 1 , 1 … k ⁢ ⁢ 1 , N - 3 k ⁢ ⁢ 2 , 1 … k ⁢ ⁢ 2 , N - 3 k ⁢ ⁢ 3 , 1 … k ⁢ ⁢ 3 , N - 3 ] × [ P ⁢ ⁢ 4 … PN ] wherein P 1 to PN are the N drive signals, (P 1 ′, P 2 ′, P 3 ′) are defined by the color input signal, and the coefficients ki,j define a color-space dependence between three primaries associated with the three drive values (P 1 , P 2 , P 3 ), and the other primaries associated with the N−3 drive signal(s) P 4 to PN as defined by a product of color coordinates of the N primaries of the N sub-pixels, and selecting, via a selection circuit, a point from the common range (VS) according to a predetermined adaptable constraint (CON), wherein the selected point immediately defines the values of the N−3 drive signal(s), and substituting the selected point into each of the three functions to determine the N drive signals (P 1 , . . . , PN), wherein the determining and selecting determines intersections of the three functions wherein the calculated intersections provide values in a space defined by the N−3 drive signal(s) which are used to determine the common range, and driving the display with the N drive signals (P 1 , . . . , PN).