US 5,510,851 AGranted

Method and apparatus for dynamic purity correction

AssigneeRadius Inc.

InventorsPeter F. Foley, Gregory E. Hale

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Abstract

The invention pertains to a method and apparatus for performing dynamic purity correction to insure that color purity is maintained across the face of a color monitor. The monitor displays a plurality of pixels, each having a particular luminescence value. Each luminescence value has several color components (E.g. red (R), green (G) and blue (B)). A grid of luminance measurements is made across the face of the monitor for each color component. From these luminance value grids, smoothly varying correction values are computed for each color component of each pixel by the interpolation of cubic splines, such as a Catmull-Rom spline. Incoming digital video signals are multiplied by corresponding correction values to insure color accuracy of the monitor. In a preferred embodiment, the calculation of correction values is repeatedly performed in real time (at the display dot clock rate) in a single monolithic RAMDAC integrated circuit to increase speed, improve fidelity, and minimize use of memory space.

Claims23

Dependent claims

A method of performing dynamic purity correction for a monitor, the monitor having a face and being capable of displaying Y rows and X columns of pixels on the face, wherein each pixel has a luminescence value for each color component displayed by the monitor, the method comprising the steps of:

measuring the luminescence value for each color component for a grid of pixels on the face of the monitor, thereby forming a first grid of luminescence values, and providing the first grid of luminescence values to a correction value calculation circuit (CVCC);
generating from the first grid of luminescence values a second grid of luminescence values suitable for subsequent interpolation, the second grid of luminescence values having vertically aligned sets of luminescence values;
interpolating each vertically aligned set of luminescence values, of the second grid, for each color component to calculate control points, wherein the control points form a control point array that has Y rows and N columns, where N is an integer less than X, and where the control point array is subsequently stored in a memory;
retrieving a row of N control points stored in the memory into an interpolator;
interpolating each row of N control points retrieved from the memory to compute a corresponding row of X correction values;
multiplying each row of correction values by a corresponding row of luminescence values of an incoming video signal to produce a set of rows of modified luminescence values for each color component of each pixel of the corresponding row of luminescence values;
and
displaying the rows of modified pixels on the monitor.

5 more elements

An apparatus for performing dynamic purity correction for a monitor, wherein the monitor displays a plurality of pixels, each of said pixels having a luminescence value for each color component displayed by the monitor, said apparatus comprising:

sensing means for measuring the luminescence value for each color component of predetermined ones of the pixels displayed by the monitor;
correction value calculation circuit (CVCC) means coupled to the sensing means, for calculating correction values for each of the pixels displayed by the monitor based upon the luminescence values measured for each color component by the sensing means;
wherein the CVCC means also receives incoming video signals and modifies these signals according to the correction values calculated and transmits the signals, after being modified, to the monitor, and wherein the CVCC means further comprises:
means for storing the luminescence values in a computer memory as a first set of grids;
and
means for interpolating the luminescence values to form the correction values.

3 more elements

A method for performing dynamic purity correction for a monitor, wherein the monitor displays a plurality of pixels, each of said pixels having a luminescence value for each color component displayed by the monitor, comprising the steps of:

measuring the luminescence value for each color component of predetermined ones of the pixels displayed by the monitor;
calculating correction values for each of the pixels displayed by the monitor based upon the luminescence values measured for each color component by the sensing means;
receiving incoming video signals;
modifying the video signals according to the correction values calculated;
and
transmitting the video signals, after said video signals have been modified according to the correction values, to the monitor, wherein the step of calculating correction values includes the steps of:
storing the luminescence values in a computer memory as a first set of grids;
interpolating the luminescence values to form the correction values.

5 more elements

Dependencies are inferred from the claim text.