Apparatus for enhancing brightness uniformity of displayed image, display apparatus, and method for displaying image

• US 10,490,145 B2
• Filed: 06/02/2017
• Issued: 11/26/2019
• Est. Priority Date: 09/21/2016
• Status: Active Grant

• Current Assignee: Beijing Smart-Aero Display Technology Company Limited
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: Zhu, Huizhong, Liu, Junguo, Sun, Shenglin
• Primary Examiner(s): Lin, Chun-Nan
• Application Number:
  US15/571,615
• Publication Number:
  US 20190130853A1
• Time in Patent Office: 907 Days
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/147 the originated light output being determined for each pixel
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: 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

Abstract

The present application discloses a method for displaying image using a display panel. The method includes receiving a frame of image data, which is divided into a first portion and a second portion based on that each sub-pixel in the first portion has an initial grayscale value smaller than that of each subpixel in the second portion. The method includes converting the frame of image data into N frames of image data. Each sub-pixel in the first portion is provided with a first grayscale value in K of the N frames and a second grayscale value in N-K of the N frames, and each sub-pixel in the second portion is retained with its initial grayscale value. N is no smaller than 2 and K varies from 1 to N−1. The method includes displaying each of the N frames of images respectively based on the N frames of image data according to a frame refreshing frequency.

Claims

1. An apparatus for enhancing brightness uniformity of displayed image, comprising:

a processor configured to convert a frame of image data, which is divided into a first portion and a second portion based on that each sub-pixel in the first portion has an initial grayscale value smaller than that of each subpixel in the second portion, into N frames of image data;

wherein the apparatus is configured to receive the frame of image data comprising a plurality of initial grayscale values respectively corresponding to a plurality of sub-pixels;

wherein each sub-pixel in the first portion is provided with a first grayscale value in K of the N frames of image data and a second grayscale value in N-K of the N frames of image data; and

each sub-pixel in the second portion is retained with its initial grayscale value in each of the N frames of image data, wherein N is an integer equal to or greater than 2 and K varies from 1 to N−

1.

2. The apparatus of claim 1, further comprising a display panel configured to display a frame of image based on each of the N frames of image data according to a frame refreshing frequency.

3. The apparatus of claim 2, wherein the display panel is configured to provide a grayscale image based on each of the plurality of initial grayscale values that is smaller than a threshold grayscale value, a maximum brightness value of the grayscale image being measured by a camera;

and

the processor is configured to deduce a set of gamma curve data comprising a set of gamma-corrected brightness values corresponding to a set of grayscale values, the first grayscale value and the second grayscale value being two adjacent grayscale values corresponding to two gamma-corrected brightness values in the set of gamma curve data.

4. The apparatus of claim 3, wherein the processor is configured to select the first grayscale value, the second grayscale value, and a value of K so that a difference between a modified brightness value for sub-pixels in the first portion having a particular initial grayscale value and a superposition value of the two gamma-corrected brightness values respectively weighted with a first ratio of K/N and a second ratio of (N-K)/N is minimal.

5. The apparatus of claim 3, wherein the modified brightness value is equal to a maximum value among all sub-pixels corresponding to the particular initial grayscale value, multiplied by a factor.

6. The apparatus of claim 5, wherein the processor is configured to select a first value smaller than 1 as the factor to obtain a first value of the modified brightness value used in a first iteration of converting the frame of image data to the N frames of image data;

and

the display panel is configured to display a frame of image based on each of the N frames of image data which is subjected to a determination whether a brightness uniformity of a displayed frame of image meets a threshold uniformity.

7. The apparatus of claim 6, wherein the processor is configured to:

select a second value larger than the first value but still smaller than 1 as the factor to obtain a second value of the modified brightness value used in a second iteration of converting the frame of image data to the N frames of image data until the brightness uniformity of the displayed frame of image based on each of the N frames of images meets the threshold uniformity; and

determine that the second value of the modified brightness value to be corresponding to the particular initial grayscale value.

8. The apparatus of claim 1, wherein N is selected to be equal to or smaller than 4.

9. The apparatus of claim 2, wherein the frame refreshing frequency is N×

60 Hz.

10. A display apparatus comprising the apparatus of claim 1.

11. A method for displaying image using a display panel, the method comprising:

receiving a frame of image data comprising a plurality of initial grayscale values respectively corresponding to a plurality of sub-pixels; and

converting the frame of image data, which is divided into a first portion and a second portion based on that each sub-pixel in the first portion has an initial grayscale value smaller than that of each subpixel in the second portion, into N frames of image data;

wherein each sub-pixel in the first portion is provided with a first grayscale value in K of the N frames of image data and a second grayscale value in N-K of the N frames of image data; and

each sub-pixel in the second portion is retained with its initial grayscale value in each of the N frames of image data, wherein N is an integer equal to or greater than 2 and K varies from 1 to N−

1.

12. The method of claim 11, further comprising displaying each of the N frames of images respectively based on the N frames of image data according to a frame refreshing frequency.

13. The method of claim 12, wherein the frame refreshing frequency is N×

60 Hz.

14. The method of claim 11, comprising displaying a grayscale image of each of the initial grayscale values that are smaller than a threshold grayscale value to measure a corresponding maximum brightness value and to deduce a set of gamma curve data comprising a set of gamma-corrected brightness values corresponding to a set of grayscale values.

15. The method of claim 14, wherein the first grayscale value and the second grayscale value are two adjacent grayscale values corresponding to two gamma-corrected brightness values in the set of gamma curve data.

16. The method of claim 15, wherein the first grayscale value, the second grayscale value, and a value of K are selected so that a difference between a modified brightness value for all sub-pixels in the first portion having a particular initial grayscale value and a superposition value of the two gamma-corrected brightness values respectively weighted with a first ratio of KN and a second ratio of (N-K)/N is minimal.

17. The method of claim 16, wherein converting the frame of image data comprises determining the modified brightness value to be equal to a maximum brightness value among all sub-pixels corresponding to the particular initial grayscale value multiplied by a factor.

18. The method of claim 17, wherein converting the frame of image data further comprises:

selecting the factor smaller than 1 to calculate a first value of the modified brightness value used in a first iteration of converting the frame of image data to the N frames of image data;

displaying an image based on each of the N frames of image data; and

determining whether a brightness uniformity of a displayed frame of image meets a threshold uniformity.

19. The method of claim 18, wherein converting the frame of image data further comprises:

increasing the factor to calculate a second value of the modified brightness value used in a second iteration of converting the frame of image data to the N frames of image data until the brightness uniformity of the displayed frame of image based on each of the N frames of images meets the threshold uniformity; and

determining that the second value of the modified brightness value to be corresponding to the particular initial grayscale value.

20. The method of claim 11, wherein N is selected to be equal to or smaller than 4.