# US 9,437,160 B2 · System and method for automatic color matching in a multi display system using sensor feedback control

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- Number: US 9,437,160 B2
- Document ID: US9437160B2
- Status: Granted
- Kind: B2
- Application number: 14/100,986
- Filed: 2013-12-09
- Published: 2014-04-17
- Granted: 2016-09-06
- Earliest claimed: 2010-07-15
- Assignees: Mersive Technologies, Inc.
- Applicants: Mersive Technologies, Inc.
- Inventors: Christopher O. Jaynes; Thomson Comer; Stephen B. Webb; Michael Tolliver
- Web page: https://patentgrep.com/patent/US9437160B2

## CPC

- G09G 5/02: characterised by the way in which colour is displayed {(details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607)}
- G06F 3/1446: {display composed of modules, e.g. video walls}
- G09G 5/12: Synchronisation between the display unit and other units, e.g. other display units, video-disc players
- H04N 1/6055: {using test pattern analysis}
- H04N 9/3147: {Multi-projection systems (video walls G06F3/1446)}
- H04N 9/3182: {Colour adjustment, e.g. white balance, shading or gamut (white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607)}
- H04N 9/3194: {including sensor feedback}
- G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)}
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0285: using tables for spatial correction of display data
- G09G 2320/0666: for control of colour parameters, e.g. colour temperature
- G09G 2320/0693: Calibration of display systems
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A system for automatic color matching of multiple displays in a multi-display system. A sensor observes the output energy of each of the displays in a multi-display system and measures the difference in the color responses for a given input color. This difference is used to derive a modification function that is applied to each display. The displays are modified accordingly, and then the color is displayed again. This process is repeated until the measured values from each of the displays are within a minimum measurement error tolerance, so that the differences in displayed colors observed among the displays are minimized.

## Claims

### Claim 1

A method for automatic color matching of a plurality of displays in a multi-display system comprising:
(a) receiving a test image on each of the a plurality of displays, wherein the test image comprises pixel color values;
(b) capturing the test image displayed on each of the displays;
(c) measuring a color response profile for each of the displays;
(d) modifying an operating mode vector, comprising the color transfer function for each of the displays, in response to measured error in the color response profile; wherein the color transfer function is modified for at least one of the displays;
(e) applying the modified operating mode vector to the displays;
wherein the operating mode vector is modified by a random sample optimization comprising:
(f) modifying display input RGB values;
(g) measuring one or more randomly sampled corresponding output values as observed by a sensor to generate a set of output and observed value pairs;
(h) comparing the observed value to a target value;
(i) computing a correction factor; and
repeating steps (f) through (i) until the measured color response profile for each of the displays is within a predetermined error tolerance.

### Claim 2 (depends on 1)

The method of claim 1, wherein the test image is the contents of the current framebuffer that would be displayed during normal operation of the display.

### Claim 3 (depends on 1)

The method of claim 1, wherein the test image is the contents of the current framebuffer that would be displayed during normal operation of the display, wherein the test image comprises pixel color values.

### Claim 4

A method for automatic color matching of a plurality of displays in a multi-display system comprising:
(a) receiving a test image on each of the a plurality of displays, wherein the test image comprises pixel color values;
(b) capturing the test image displayed on each of the displays;
(c) measuring a color response profile for each of the displays;
(d) modifying an operating mode vector, comprising the color transfer function for each of the displays, in response to measured error in the color response profile; wherein the color transfer function is modified for at least one of the displays;
(e) applying the modified operating mode vector to the displays;
wherein the operating mode vector is modified by a modified gradient descent optimization comprising:
(f) modifying display input RGB values;
(g) measuring the corresponding output value as observed by a sensor to generate an observed value;
(h) comparing the observed value to a target value;
(i) computing a correction factor; and
repeating steps (f) through (i) until the measured color response profile for each of the displays is within a predetermined error tolerance.

### Claim 5 (depends on 4)

The method of claim 4, wherein the test image is the contents of the current framebuffer that would be displayed during normal operation of the display, wherein the test image comprises pixel color values.

### Claim 6

A method for automatic color matching of a plurality of displays in a multi-display system comprising:
(a) sending a test image to each of the a plurality of displays;
(b) capturing the test image displayed on each of the displays;
(c) measuring a color response profile for each of the displays;
(d) modifying an operating mode vector, comprising the color transfer function for each of the displays, in response to measured error in the color response profile;
wherein the color transfer function is modified for at least one of the displays;
(e) applying the modified operating mode vector to the displays;
wherein the operating mode vector is modified by a modified gradient descent optimization comprising:
(f) modifying display input RGB values;
(g) measuring the corresponding output value as observed by a sensor to generate an observed value;
(h) comparing the observed value to a target value;
(i) computing a correction factor; and
repeating steps (f) through (i) until the measured color response profile for each of the displays is within a predetermined error tolerance.

### Claim 7 (depends on 6)

The method of claim 6, wherein the color matching is based on a per-pixel intensity on each color channel, wherein the operating mode vector maps a pixel location to an R,G,B attenuation value for each location in the display.

### Claim 8 (depends on 6)

The method of claim 6, wherein the color matching is performed by using a per-pixel color correction based on the location of each pixel, wherein the operating mode vector maps a pixel location to a modified RGB value.

### Claim 9 (depends on 6)

The method of claim 6, wherein the test image is the contents of the current framebuffer that would be displayed during normal operation of the display, wherein the test image comprises pixel color values.