# US 7,576,750 B2 · Method and arrangement for optimizing a luminance characteristic curve

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- Number: US 7,576,750 B2
- Document ID: US7576750B2
- Status: Granted
- Kind: B2
- Application number: 10/922,976
- Filed: 2004-08-23
- Published: 2006-02-23
- Granted: 2009-08-18
- Earliest claimed: 2003-08-21
- Assignees: EIZO Corporation
- Inventors: Wolfgang Eckhardt; Andreas Kaercher; Uwe Nagel; Hartmut Schulz
- Web page: https://patentgrep.com/patent/US7576750B2

## CPC

- H04N 1/6088: {by viewing conditions, i.e. conditions at picture output}
- H04N 1/407: Control or modification of tonal gradation or of extreme levels, e.g. background level
- H04N 5/58: in dependence upon ambient light
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A method and an arrangement for optimizing the luminance characteristic curve for a display system using a lookup table. Digitized video levels are supplied to this lookup table and are optimized using correction values stored in the lookup table. With suitable means, the luminance characteristic curve can be easily adapted to standards and/or custom specifications. The memory requirement is low, since it is not necessary to provide different lookup tables for different ambient luminosities or selected reproduction models (curves).

## Claims

### Claim 1

A method for adjusting a luminance characteristic curve for a display system comprising:
storing desired luminance characteristic values corresponding to a desired luminance characteristic curve in a lookup table;
storing natural response luminance values in said lookup table corresponding to a luminance response of said display system to test images without an influence of ambient light;
detecting ambient light illumination of said display system during normal operation with a brightness sensor;
adjusting a range of luminances output by said display system based on the detected ambient light illumination;
scaling said stored natural response luminance values to correspond to said adjusted range of luminances output by said display system;
storing video input levels corresponding to a video signal in said lookup table;
calculating adjusted video output levels which correspond, respectively, to said video input levels; and
supplying said adjusted video output levels to said display system;
wherein said adjusted video output levels are calculated by a calculation procedure comprising:
determining an adjusted luminance level of said display system for each video input level based on said stored desired luminance characteristic values; and
calculating a corresponding adjusted video output level necessary to achieve said adjusted luminance level based on said stored natural response luminance values.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the desired luminance characteristic curve is based on at least one of the DICOM, CIELAB, or LOG Luminance standards.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the desired luminance characteristic curve is a custom-tailored luminance characteristic curve.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the desired luminance characteristic curve is selected by a menu-driven selection method with a selection mask displayed on a display unit.

### Claim 5

An apparatus for adjusting a luminance characteristic curve for a display system comprising:
a memory configured to store a lookup table;
wherein said lookup table comprises desired luminance characteristic values corresponding to a desired luminance characteristic curve; and
wherein said lookup table further comprises natural response luminance values corresponding to a luminance response of said display system to test images without an influence of ambient light;
a detector configured to detect ambient light illumination of said display system during normal operation;
a controller configured to adjust a range of luminances output by said display system based on the detected ambient light illumination;
a processor configured to scale said stored natural response luminance values to correspond to said adjusted range of luminances output by said display system;
an input device configured to input a video signal;
a video signal processor configured to store video input levels corresponding to said video signal in said lookup table;
a calculator configured to calculate adjusted video output levels which correspond, respectively, to said video input levels; and
an output device configured to output said adjusted video output levels to said display system;
wherein said video output levels are calculated by a calculation procedure comprising:
determining an adjusted luminance level of said display system for each video input level based on said stored desired luminance characteristic values;
calculating a corresponding adjusted video output level necessary to achieve said adjusted luminance level based on said stored natural response luminance values.

### Claim 6 (depends on 5)

The apparatus according to claim 5, wherein the desired luminance characteristic values are based on at least one of the DICOM, CIELAB, or LOG Luminance standards.

### Claim 7 (depends on 5)

The apparatus according to claim 5, wherein the desired luminance characteristic values are based on a custom-tailored luminance characteristic curve.

### Claim 8 (depends on 5)

The apparatus according to claim 5, wherein the desired luminance characteristic values are selected by a menu-driven selection method with a selection mask displayed on a display unit.

### Claim 9 (depends on 5)

The apparatus according to claim 5, wherein said lookup table is a component of a graphics processor.

### Claim 10 (depends on 5)

The apparatus according to claim 5, wherein said display system is a component of a medical device.