Enhanced lookup of display driving values

摘要

Approximation errors commonly occur when color transformation values stored in color look-up tables are interpolated to produce color display drive signals, since the stored transformation values typically correspond to non-linear functions. Such errors can be reduced by applying a pre-indexing function to the transformation values before they are stored in the look-up table, and by applying the same function to values extracted from the table during look-up operations. Alternatively, such errors can be reduced by providing one or more additional look-up tables to achieve higher order (i.e. more accurate) interpolation results that are achievable by interpolation of values stored in a single look-up table.

主权项

1. A method of utilizing a lookup table generated to transform an input signal X into an output signal G(X), the method comprising:
applying the input signal X to the lookup table to produce a first output signal H(X); applying a function P( ), where P( ) cannot equal 0 or 1 to the input signal X to produce a second output signal P(X); and multiplying the first and second output signals to produce a product H(X)·P(X);further comprising adding a constant C to the product to produce the output signal G(X)=H(X) P(X)+C;wherein the input signal X has three components X1, X2 and X3, the method further comprising:
in the lookup table, 3D interpolating the input signal components X1, X2 and X3 to produce the first output signal as H(X)=H(X1,X2,X3); wherein: the applying a function P(·) step further comprises applying the function P(·) to a selected ith one of the input signal components X1, X2 or X3 to produce the second output signal as P(X)=P(Xi) where i=1, 2 or 3; the product H(X)·P(X) further comprises H(X)·P(X)=H(X1,X2,X3)·P(Xi); and the output signal G(X) further comprises G(X)=G(X1,X2,X3)=H(X1,X2,X3)·P(Xi)+C.