Method for luminance compensation of liquid crystal display and its device

• US 7,317,462 B2
• Filed: 03/29/2004
• Issued: 01/08/2008
• Est. Priority Date: 03/29/2004
• Status: Expired due to Fees

• Current Assignee: Vastview Technologies, Inc.
• Original Assignee: Vastview Technologies, Inc.
• Inventors: Lu, Yih-Liang, Chen, Yi-Fan, Shen, Yuh-Ren, Chen, Cheng-Jung
• Primary Examiner(s): Mengistu; Amare
• Assistant Examiner(s): Nadkarni; Sarvesh J
• Application Number:
  US10/810,621
• Publication Number:
  US 20050212736A1
• Time in Patent Office: 1,380 Days
• Field of Search: 345/690, 345/89
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A method for luminance compensation of liquid crystal display includes: measuring the original gamma curve of the panel, setting a target gamma curve, inputting an initial gray level to obtain a luminance corresponding to the target gamma curve, finding the adjusted gray level for expressing the luminance from the original gamma curve, repeating the steps stated above to make a lookup table containing plural groups of proportion array. Then calculating the quantity distribution of input gray levels of images, selecting a corresponding proportion array from the lookup table according to the proportion value between dark level and bright level, substituting the adjusted gray levels in the proportion array for the input gray levels, outputting the adjusted gray levels for adjusting the signal intensity can improve the image quality. The method and the device for luminance compensation can adjust the intensity of input signals to obtain better image quality and suit for the image adjustment of various liquid crystal displays or similar displays.

Claims

1. A method for luminance compensation of liquid crystal display including the following steps:

(1) measuring an original gamma curve of a panel;

(2) setting a target gamma curve;

(3) inputting an initial gray level to obtain a luminance corresponding to the target gamma curve and finding an adjusted gray level for expressing a luminance from the original gamma curve;

(4) repeating (2) and (3) steps to produce plural groups of initial gray levels and plural groups of adjusted gray levels and set the plural groups of adjusted gray levels into a proportion array;

(5) repeating (2), (3), and (4) steps to produce plural groups of proportion arrays from different target curves and make a lookup table;

(6) calculating a quantity distribution of input gray levels of images;

(7) respectively calculating a dark level proportion and a bright level proportion;

(8) selecting a corresponding proportion array according to the value of dark level proportion from a lookup table of dark levels and substituting the adjusted gray level in the proportion array for the input gray level;

(9) selecting a corresponding proportion array according to the value of bright level proportion from a lookup table of bright levels and substituting the adjusted gray level in the proportion array for the input gray level; and

(10) outputting the adjusted gray levels for adjusting a signal intensity to improve the image quality;

whereby the method being able to adjust the input signal intensity and obtain better image quality and wherein the dark level proportion is the ratio of the gray level quantity in a dark level interval to a total gray level quantity, and the range of a dark level interval is from below a specific value in a total gray level range;

the bright level proportion is the ratio of the gray level quantity in bright level interval to the total gray quantity, and the range of the bright level interval is from above a specific value in the total gray level range.

2. The method for luminance compensation of liquid crystal display as claimed in claim 1, wherein the range of the dark level interval is the front quarter of the total gray level range;

the range of the bright level interval is the rear quarter of the total gray level range.

3. The method for luminance compensation of liquid crystal display as claimed in claim 1, wherein the dark level lookup table consists of a plurality of input gray levels and plural groups of proportion arrays, each input gray level can correspond to an adjusted gray level in proportion array;

the bright level lookup consists of a plurality of input gray levels and plural groups of proportion arrays, each input gray level can correspond to an adjusted gray level in proportion array.

4. The method for luminance compensation of liquid crystal display as claimed in claim 1, wherein the corresponding method between dark level proportion and proportion array includes taking the dark level proportion into a dark level transfer function to get a dark level LUT intensity, the dark level LUT intensity being corresponded to the proportion array in dark level lookup table, substituting the adjusted gray level in the proportion array for the input gray level;

the corresponding method between bright level proportion and proportion array includes taking the bright level proportion into a bright level transfer function to get a bright level LUT intensity, the bright level LUT intensity corresponding to the proportion array in bright level lookup table, substituting the adjusted gray level in the proportion array for the input gray level.

5. The method for luminance compensation of liquid crystal display as claimed in claim 4, wherein the dark level or the bright level transfer function is a gradually increasing function, wherein the higher the dark level or the bright level proportion, the larger the dark level or the bright level LUT intensity.

6. The method for luminance compensation of liquid crystal display as claimed in claim 1, wherein the gray levels between the adjusted gray levels are obtained by interpolation.

7. A method for luminance compensation of liquid crystal display including the following steps:

(1) calculating a quantity distribution of input gray levels of images;

(2) respectively calculating a dark level proportion and a bright level proportion;

(3) selecting a corresponding proportion array from a dark level lookup table according to the value of the dark level proportion, and substituting an adjusted gray levels in the proportion array for the input gray levels;

(4) selecting a corresponding proportion array from a bright level lookup table according to the value of the bright level proportion, and substituting adjusted gray levels in the proportion array for the input gray levels; and

(5) outputting the adjusted gray levels for adjusting the signal intensity to improve the image quality;

whereby the method being able to adjust the intensity of input signals and obtain better image quality and wherein the dark level proportion is the ratio of the gray level quantity in the dark level interval to a total gray level quantity, and the range of a dark level interval is from below a specific value in a total gray level range;

the bright level proportion is the ratio of the gray level quantity in the bright level interval to the total gray level quantity, and the range of the bright level interval is from above a specific value in the total gray level range.

8. The method for luminance compensation of liquid crystal display as claimed in claim 7, wherein the range of the dark level intervals is the front quarter of the total gray level range;

the range of the bright level interval is the rear quarter of the total gray level range.

9. The method for luminance compensation of liquid crystal display as claimed in claim 7, wherein the dark level lookup table consists of a plurality of input gray levels and plural groups of proportion arrays, each input gray level corresponds to an adjusted gray level in the proportion array;

the bright level lookup table consists of a plurality of input gray levels and plural groups of proportion arrays, each input gray level corresponds to an adjusted gray level in the proportion array.

10. The method of luminance compensation of liquid crystal display as claimed in claim 7, wherein the corresponding method between the dark level proportion and the proportion array includes:

taking the dark level proportion into a dark level transfer function to obtain a dark level LUT intensity, the dark level LUT intensity corresponding to the proportion array in the dark level lookup table, substituting the adjusted gray levels in the proportion array for the input gray levels;

the corresponding method between bright level proportion and the proportion array includes;

taking the bright level proportion into a bright level transfer function to get a bright level LUT intensity, the bright level LUT intensity corresponding to the proportion array in the bright level lookup table, substituting the adjusted gray levels in the proportion array for the input gray levels.

11. The method for luminance compensation of liquid crystal display as claimed in claim 10, wherein the dark level, bright level transfer function is a gradually increasing function.

12. The method for luminance compensation of liquid crystal display as claimed in claim 7, wherein the gray levels between the adjusted gray levels are obtained by interpolation.