Method for processing images in liquid crystal display

• US 8,217,888 B2
• Filed: 04/16/2008
• Issued: 07/10/2012
• Est. Priority Date: 10/18/2007
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Chien, Ming-Fon, Jou, Ming-Jong, Hsieh, Yao-Jen, Ho, Yu-Hsi
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): EURICE, MICHAEL
• Application Number:
  US12/081,442
• Publication Number:
  US 20090102781A1
• Time in Patent Office: 1,546 Days
• Field of Search: 345 60-104, 345/168, 345/211, 345/214, 345600-604, 345671-672, 345690-694
• US Class Current: 345/102
• 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 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A method for processing images in a liquid crystal display is provided. The method includes the steps of: acquiring a backlight index according to an image; adjusting a backlight according to the backlight index; acquiring a reference gray level according to the adjusted backlight, wherein the reference gray level lies in between a first gray level boundary and a second gray level boundary; transferring a gray level of the image into a corresponding output gray level according to the backlight index when the gray level of the image lying in between the reference gray level and the first gray level boundary; and transferring the gray level of the image into another corresponding output gray level according to a linear relationship when the gray level of the image lying in between the reference gray level and the second gray level boundary.

Claims

1. A method for processing images in a liquid crystal display, the method comprising:

(a) acquiring a backlight index in relation to gray levels of an image;

(b) adjusting a backlight according to the backlight index;

(c) acquiring a reference gray level configured to be compared with the gray levels of the image, wherein the reference gray level varies with a backlight brightness of the adjusted backlight corresponding to the backlight index, and the reference gray level lies in between a first gray level boundary and a second gray level boundary;

(d) transferring a gray level of the image into a corresponding output gray level according to a transferring relationship having a first slope when the gray level of the image lies in between the reference gray level and the first gray level boundary; and

(e) transferring the gray level of the image into another corresponding output gray level according to a linear relationship having a second slope different from the first slope when the gray level of the image lying in between the reference gray level and the second gray level boundary;

wherein the reference gray level is determined by the following equation;

2. The method as claimed in claim 1, wherein brightness of the backlight is adjusted to be enhanced according to the backlight index, and the first gray level boundary is lower than the second gray level boundary.

3. The method as claimed in claim 2, wherein the reference gray level lies in between the second gray level boundary and a middle gray level that lies in between the first gray level boundary and the second gray level boundary.

4. The method as claimed in claim 2, wherein the first gray level boundary is a lowest gray level of an image frame, and the second gray level boundary is a highest gray level of the image frame.

5. The method as claimed in claim 1, wherein step (d) further comprises:

transferring the gray level of the image into the corresponding output gray level according to the gamma value and the brightness of the adjusted backlight.

6. The method as claimed in claim 1, wherein step (b) further comprises:

generating a corresponding pulse width modulation signal according to the backlight index; and

adjusting the backlight by the pulse width modulation signal.

7. The method as claimed in claim 1, wherein step (a) further comprises:

determining the backlight index in relation to at least numbers of the gray levels occurring in the image.

8. The method as claimed in claim 1, wherein in step (d), the transferring relationship between the gray level of the image and the corresponding output gray level is associated with a gamma value and a backlight brightness corresponding to the backlight index.

9. The method as claimed in claim 1, wherein in step (e), the linear relationship between the gray level of the image and the corresponding output gray level is associated with a ratio of a highest output gray level compared to a highest input gray level.

10. The method as claimed in claim 1, wherein when the gray level of the image lies in between the reference gray level and the first gray level boundary, the output gray level is determined by the following equation:

11. The method as claimed in claim 1, wherein when the gray level of the image lies in between the reference gray level and the second gray level boundary, the output gray level is determined by the following equation:

13. The method as claimed in claim 10, wherein when the gray level of the image lies in between the reference gray level and the second gray level boundary, the output gray level is determined by the following equation:

12. A method for processing images in a liquid crystal display, the method comprising:

transferring a gray level of an image into a corresponding output gray level according to a transferring relationship having a first slope when the gray level of the image lies in between a reference gray level and one of a lowest gray level and a highest gray level of an image frame; and

transferring the gray level of the image into another corresponding output gray level according to a linear relationship having a second slope different from the first slope when the gray level of the image lies in between the reference gray level and the other of the lowest gray level and the highest gray level of the image frame;

wherein the variation of the first slope is greater than the variation of the second slope;

wherein the reference gray level is determined by the following equation;

14. The method as claimed in claim 12, wherein

when the gray level of the image lies in between the reference gray level and another of the lowest gray level and the highest gray level of the image frame, the output gray level is determined by the following equation:

15. The method as claimed in claim 12, wherein

when the gray level of the image lies in between the reference gray level and one of the lowest gray level and the highest gray level of the image frame, the output gray level is determined by the following equation:

16. The method as claimed in claim 15, wherein

when the gray level of the image lies in between the reference gray level and another of the lowest gray level and the highest gray level of the image frame, the output gray level is determined by the following equation:

17. A method for processing images in a liquid crystal display, the method comprising:

(a) acquiring a backlight index in relation to gray levels of an image;

(b) adjusting a backlight according to the backlight index;

(c) acquiring a reference gray level configured to be compared with the gray levels of the image, wherein the reference gray level varies with a backlight brightness of the adjusted backlight corresponding to the backlight index, and the reference gray level lies in between a first gray level boundary and a second gray level boundary;

(d) transferring a gray level of the image into a corresponding output gray level according to a transferring relationship having a first slope when the gray level of the image lies in between the reference gray level and the first gray level boundary; and

(e) transferring the gray level of the image into another corresponding output gray level according to a linear relationship having a second slope different from the first slope when the gray level of the image lying in between the reference gray level and the second gray level boundary;

wherein when the gray level of the image lies in between the reference gray level and the first gray level boundary, the output gray level is determined by the following equation;

18. The method as claimed in claim 17, wherein step (c) further comprises:

acquiring the gamma value according to the backlight index; and

acquiring the reference gray level according to the gamma value and brightness of the adjusted backlight.

19. The method as claimed in claim 17, wherein step (b) further comprises:

generating a corresponding pulse width modulation signal according to the backlight index; and

adjusting the backlight by the pulse width modulation signal.

20. The method as claimed in claim 17, wherein step (a) further comprises:

determining the backlight index in relation to at least numbers of the gray levels occurring in the image.