Display method and device of dynamically controlling backlight

Patent metadata

Field	Value
Publication number	US-2018357967-A1
Application number	US-201715556494-A
Country	US
Kind code	A1
Filing date	Jul 21, 2017
Priority date	Jun 8, 2017
Publication date	Dec 13, 2018
Grant date	—

Abstract

A display method and a display device of dynamically controlling backlight are provided. The present disclosure obtains a modified grayscale value of the input image in each of partitions by using the whole backlight reference value, the RGBW grayscale values of the input image in each of partitions, the normalized backlight output brightness value, and the spatial distribution function of the backlight brightness in each of partitions. The normalized backlight output brightness value of each of partitions is processed as a real backlight output brightness value which is outputted to a backlight driving circuit. The modified grayscale value is processed as a real grayscale value and then the real grayscale value is outputted to a display panel for display. The backlight and image grayscale of each of partitions are adjusted dynamically, thereby improving contrast space and power consumption and further, normally displaying the HDR contents in the HDR display.

First claim

What is claimed is:

1 . A display method of dynamically controlling backlight, comprising:
normalizing a red (R) grayscale value, a green (G) grayscale value, and a blue (B) grayscale value of an obtained whole frame of an input image, and dividing the whole frame of the input image into a plurality of partitions; obtaining a normalized backlight output brightness value of each of the plurality of partitions by using the mean of a grayscale peak value of the input image and a brightness gain of the input image in each of the plurality of partitions; obtaining a modified grayscale value of the input image in each of the plurality of partitions by using a whole backlight reference value, the R, G, and B grayscale values and a white (W) grayscale value of the input image in each of the plurality of partitions, the normalized backlight output brightness value, and a spatial distribution function of the backlight brightness in each of the plurality of partitions wherein the RGB grayscale values of the input image are converted into the RGBW grayscale values of the input image by using the brightness gain; the whole backlight reference value is calculated based on the mean of the grayscale peak value of the whole frame of the input image; processing the normalized backlight output brightness value of each of the plurality of partitions to be a real backlight output brightness value; outputting the real backlight output brightness value to a backlight driving circuit; processing the modified grayscale value to be a real grayscale value and outputting the real grayscale value to a display panel for display.

2 . The method of claim 1 , wherein the whole backlight reference value is BLUconst=min(1,f(Lmean)),
where BLUconst indicates the whole backlight reference value; Lmean indicates the mean of the grayscale peak value of the whole frame of the input image in each of the plurality of partitions; when Lmean≤GT stands, f(Lmean)=1 is true; when Lmean=1 stands, f(Lmean)=LT is true; when GT≤Lmean≤1 stands, f(Lmean)∈[LT,1] is true; f(Lmean)∈[LT,1] is the function Lmean of monotonical decrease; LT indicates a backlight brightness threshold value; GT indicates a threshold value of the mean of the grayscale peak value.

3 . The method of claim 1 , wherein the RGBW grayscale values of the input image are Ro=gain*Rin−Wo; Go=gain*Gin−Wo; Bo=gain*Bin; Wo=g(Rin,Gin,Bin),
where Ro, Go, Bo, and Wo respectively correspond to the converted red, green, blue, and white grayscale values of the input image in each of the plurality of partitions; Rin, Gin, and Bin respectively correspond to the red, green, and blue grayscale values of the input image in each of the plurality of partitions before the red, green, and blue grayscale values are converted; gain indicates the brightness gain.

4 . The method of claim 1 , wherein the normalized backlight output brightness value in each of the plurality of partitions is BLUout=L′mean/gain,
where BLUout indicates the normalized backlight output brightness value in each of the plurality of partitions; L′mean indicates the mean of the grayscale peak value of the input image in each of the plurality of partitions; gain indicates the brightness gain.

5 . The method of claim 1 , wherein the modified grayscale value of the input image in each of the plurality of partitions is Lout=min(1,BLUconst*Lo/(BLUout*h(x,y))),
where Lout indicates the modified grayscale value of the input image in each of the plurality of partitions, where Lo indicates the grayscale value of the input image in each of the plurality of partitions before being modified, comprising the Ro, Go, Bo and Wo; BLUconst indicates the whole backlight reference value; BLUout indicates the normalized backlight output brightness value in each of the plurality of partitions; the function h(x,y) indicates the spatial distribution function of the backlight brightness in each of the plurality of partitions.

6 . The method of claim 1 , wherein the real backlight output brightness value is BLU=BLUout*BLUmax,
where BLU indicates the real backlight output brightness value in each of the plurality of partitions; BLUout indicates the normalized backlight output brightness value in each of the plurality of partitions; BLUmax indicates a maximal value of the backlight brightness in each of the plurality of partitions.

7 . The method of claim 1 , wherein the grayscale peak value is a maximal value of the RGB grayscale.

8 . The method of claim 1 , wherein the dividing the whole frame of the input image into the plurality of partitions comprises:
dividing the whole frame of the input image into the plurality of partitions according to the method of backlight partition.

9 . A display device, comprising:
a backlight driving circuit; a processor, coupled to the backlight driving circuit and configured to execute instructions to perform operations of: normalizing a red (R) grayscale value, a green (G) grayscale value, and a blue (B) grayscale value of an obtained whole frame of an input image, and dividing the whole frame of the input image into a plurality of partitions; obtaining a normalized backlight output brightness value of each of the plurality of partitions by using the mean of a grayscale peak value of the input image and a brightness gain of the input image in each of the plurality of partitions; obtaining a modified grayscale value of the input image in each of the plurality of partitions by using a whole backlight reference value, the R, G, and B grayscale values and a white (W) grayscale value of the input image in each of the plurality of partitions, the normalized backlight output brightness value, and a spatial distribution function of the backlight brightness in each of the plurality of partitions wherein the RGB grayscale values of the input image are converted into the RGBW grayscale values of the input image by using the brightness gain; the whole backlight reference value is calculated based on the mean of the grayscale peak value of the whole frame of the input image; processing the normalized backlight output brightness value of each of the plurality of partitions to be a real backlight output brightness value; outputting the real backlight output brightness value to a backlight driving circuit; processing the modified grayscale value to be a real grayscale value and outputting the real grayscale value to a display panel for display.

10 . The display device of claim 9 , wherein the processor exexutes the instructions to calculate the whole backlight reference value BLUconst according to a formula:
BLUconst=min(1, f (Lmean)), where BLUconst indicates the whole backlight reference value; Lmean indicates the mean of the grayscale peak value of the whole frame of the input image in each of the plurality of partitions; when Lmean≤GT stands, f(Lmean)=1 is true; when Lmean=1 stands, f(Lmean)=LT is true; when GT≤Lmean≤1 stands, f(Lmean)∈[LT,1] is true; f(Lmean)∈[LT,1] is the function Lmean of monotonical decrease; LT indicates a backlight brightness threshold value; GT indicates a threshold value of the mean of the grayscale peak value.

11 . The display device of claim 9 , wherein the processor exexutes the instructions to calculate the RGBW grayscale values of the input image according to formulas: Ro=gain*Rin−Wo; Go=gain*Gin−Wo; Bo=gain*Bin; Wo=g(Rin,Gin,Bin),
where Ro, Go, Bo, and Wo respectively correspond to the converted red, green, blue, and white grayscale values of the input image in each of the plurality of partitions; Rin, Gin, and Bin respectively correspond to the red, green, and blue grayscale values of the input image in each of the plurality of partitions before the red, green, and blue gra

Assignees

• Wuhan China Star Optoelectronics Technology Co Ltd

Inventors

• Zha Guowei

Classifications

• G09G2320/0276

  for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction · CPC title

• G09G3/342 Primary

  using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines · CPC title

• G09G2320/062

  Adjustment of illumination source parameters · CPC title

• G09G2340/06

  Colour space transformation · CPC title

• G09G2340/04

  Changes in size, position or resolution of an image · CPC title