# US 2017/0256192 A1 · Reducing lcd power consumption by preferentially dimming individual colors

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- Number: US 2017/0256192 A1
- Document ID: US20170256192A1
- Status: Published application
- Kind: A1
- Application number: 15/062,809
- Filed: 2016-03-07
- Published: 2017-09-07
- Earliest claimed: 2016-03-07
- Assignees: Dell Products L.P.
- Applicants: Dell Products L.P.
- Inventors: Lawrence E. Knepper; Yagiz Can Yildiz
- Web page: https://patentgrep.com/patent/US20170256192A1

## CPC

- G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)}
- G09G 3/2092: {Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto (suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165)}
- G09G 3/32: semiconductive, e.g. using light-emitting diodes [LED]
- G09G 3/3413: {Details of control of colour illumination sources}
- G09G 3/3607: {for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels (display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127)}
- G09G 2320/0626: for control of overall brightness
- G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other
- G09G 2330/021: Power management, e.g. power saving
- G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data
- 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)

## Abstract

A display device may include a respective backlight controller for each color in a color model. A screen driver for the display device may produce a histogram of brightness values for each color in the pixel data for an image frame, and may reduce the brightness of backlighting elements of the display device for individual colors when the histogram data indicates that maximum brightness is not required. For example, based on a backlight control value or signal sent to the corresponding backlight controller, the intensity of backlighting elements for one color may be turned down, or even off, for a particular image frame while the backlighting elements for other colors remain fully powered. The screen driver may make an adjustment to the pixel data to compensate for the dimming of the backlighting elements by modifying the color values in a color lookup table.

## Claims

### Claim 1

A method for reducing power consumption in a display device, comprising:
receiving pixel data representing an image frame, the pixel data encoding colors of pixels in the image frame in accordance with a color model comprising a plurality of color components;
analyzing the pixel data, the analyzing including:
producing a respective histogram of brightness levels in the image frame for each of the color components of the color model; and
determining, for each color component, a respective backlight control value based on the histogram for the color component;
sending, for each color component, the backlight control value for the color component to a respective backlight controller for the color component; and
controlling, for each color component, intensity for each of a plurality of illuminating elements of the display device corresponding to the color component based on the backlight control value for the color component.

### Claim 2 (depends on 1)

The method of claim 1, wherein the histogram for each color component indicates a minimum, maximum, or average brightness level for the color component in the pixel data.

### Claim 3 (depends on 1)

The method of claim 1, wherein the plurality of illuminating backlight elements for each color component comprises one or more strings of light-emitting diodes (LEDs) that emit light having the color of the color component.

### Claim 4 (depends on 1)

The method of claim 1, wherein the plurality of illuminating backlight elements for each color component comprises one or more strings of light-emitting diodes (LEDs) that backlight a subset of the image frame when displayed on the display device.

### Claim 5 (depends on 1)

The method of claim 1, wherein:
the analyzing further includes determining a desired maximum brightness level for the color component in at least a portion of the image frame; and
determining the backlight control value for the color component is dependent on the desired maximum brightness level.

### Claim 6 (depends on 1)

The method of claim 1, wherein:
the analyzing further includes applying a mathematical or logical function to at least a portion of the brightness values in the histogram for the color component; and
determining the backlight control value for the color component is dependent on results of the applying.

### Claim 7 (depends on 1)

The method of claim 1, wherein:
for one of the color components, controlling the intensity for each of the plurality of illuminating elements of the display device corresponding to the color component includes reducing the brightness of the plurality of illuminating elements from a maximum brightness level; and
the method further comprises:
determining an adjustment to be made to at least a portion of the color values in a color lookup table to compensate for reducing the brightness; and
applying the adjustment to the color values in the color lookup table.

### Claim 8

An article of manufacture comprising a non-transitory computer-readable medium storing instructions, that, when executed by a processor of a display device, cause the processor to:
access pixel data representing an image frame, the pixel data encoding colors of pixels in the image frame in accordance with a color model comprising a plurality of color components;
produce, based on the pixel data, a respective histogram of brightness levels in the image frame for each of the color components of the color model;
determine, for each color component, a respective backlight control value based on the histogram for the color component, the backlight control value to control the intensity for each of a plurality of illuminating elements of the display device; and
send, for each color component, the backlight control value for the color component to a respective backlight controller for the color component.

### Claim 9 (depends on 8)

The article of manufacture of claim 8, wherein the plurality of illuminating backlight elements for each color component comprises one or more strings of light-emitting diodes (LEDs) that emit light having the color of the color component.

### Claim 10 (depends on 8)

The article of manufacture of claim 8, wherein the plurality of illuminating backlight elements for each color component comprises one or more strings of light-emitting diodes (LEDs) that backlight a subset of the image frame when displayed on the display device.

### Claim 11 (depends on 8)

The article of manufacture of claim 8, wherein:
the instructions further include instructions to determine a desired maximum brightness level for the color component in at least a portion of the image frame; and
the determination of the backlight control value for the color component is dependent on the desired maximum brightness level.

### Claim 12 (depends on 8)

The article of manufacture of claim 8, wherein:
for one of the color components, the instructions further include instructions to apply a mathematical or logical function to at least a portion of the brightness values in the histogram for the color component; and
the determination of the respective backlight control value for the color component is dependent on results of the application of the mathematical or logical function.

### Claim 13 (depends on 8)

The article of manufacture of claim 8, wherein:
for one of the color components, the instructions to control the intensity for each of the plurality of illuminating elements of the display device corresponding to the color component include instructions to reduce the brightness of the plurality of illuminating elements from a maximum brightness level; and
the instructions further include instructions to:
determine an adjustment to be made to at least a portion of the color values in a color lookup table to compensate for the reduction in brightness; and
apply the adjustment to the color values in the color lookup table.

### Claim 14

A screen driver, comprising:
a plurality of backlight controllers, each of which controls a respective collection of illuminating elements of a display device that emit light of the same given one of a plurality of colors of a color model; and
a processor having access to a memory, wherein the memory stores instructions that, when executed by the processor, cause the processor to:
access pixel data representing an image frame, the pixel data encoding colors of pixels in the image frame in accordance with the color model;
produce, based on the pixel data, a respective histogram of brightness levels in the image frame for each color of the color model;
determine, for each color, a respective backlight control value based on the histogram for the color, the backlight control value to control the intensity for the collection of illuminating elements of a display device that emit light of the color; and
send, for each color, the backlight control value for the color to a backlight controller that controls a collection of illuminating elements of a display device that emit light of the color.

### Claim 15 (depends on 14)

The screen driver of claim 14, wherein the histogram for each color indicates a minimum, maximum, or average brightness level for the color in the pixel data.

### Claim 16 (depends on 14)

The screen driver of claim 14, wherein the collection of illuminating elements that emit light of a given color comprises one or more strings of light-emitting diodes (LEDs) that emit light of the given color.

### Claim 17 (depends on 14)

The screen driver of claim 14, wherein the collection of illuminating elements that emit light of a given color comprises one or more strings of light-emitting diodes (LEDs) that backlight a subset of the image frame when displayed on the display device.

### Claim 18 (depends on 14)

The screen driver of claim 14, wherein:
for one of the colors, the instructions further include instructions to determine a desired maximum brightness level for the color in at least a portion of the image frame; and
the determination of the backlight control value for the color is dependent on the desired maximum brightness level.

### Claim 19 (depends on 14)

The screen driver of claim 14, wherein:
for one of the colors, the instructions further include instructions to apply a mathematical or logical function to at least a portion of the brightness values in the histogram for the color; and
the determination of the backlight control value for the color is dependent on results of the application of the mathematical or logical function.

### Claim 20 (depends on 14)

The screen driver of claim 14, wherein, for a given one of the colors, the instructions further include instructions to:
reduce the brightness of the plurality of illuminating elements that emit light of the given color from a maximum brightness level;
determine an adjustment to be made to at least a portion of the color values in a color lookup table to compensate for the reduction in brightness; and
apply the adjustment to the color values in the color lookup table.