Gamma curve compensating method, gamma curve compensating circuit and display system using the same

Patent metadata

Field	Value
Publication number	US-9443489-B2
Application number	US-37073009-A
Country	US
Kind code	B2
Filing date	Feb 13, 2009
Priority date	Apr 28, 2008
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

An exemplary gamma curve compensating method is used in a displaying process of a display system for inserting a plurality of grey-scale images to adjust the displaying quality of the display system. A grey-scale luminance of each grey-scale image is one of the grey-scales. The gamma curve compensating method includes: providing a plurality of look-up tables (LUTs) according to the different grey-scales; selecting a specific grey-scale of the different grey-scales as a grey-scale luminance of one of the grey-scale images and accordingly selecting a specific LUT of the LUTs corresponding to the specific grey-scale; and performing a gamma-curve compensating based on the specific LUT to keep the gamma curve of the display system invariable in the displaying process. A gamma curve compensating circuit and a display system for performing the gamma curve compensating method are also provided in the present invention.

First claim

What is claimed is:

1. A gamma curve compensating circuit used in a display system, comprising:
an image generating circuit, generating an original output image signal according to an input image signal received by the display system;
a grey-scale insertion determining circuit, determining a plurality of grey-scale luminance of a grey-scale image to be inserted according to the input image signal and outputting the grey-scale image;
a multiplexer, having a first input terminal electrically coupled to the grey-scale insertion determining circuit and a second input terminal electrically coupled to the image generating circuit, and the multiplexer being used for providing an original display signal comprising the grey-scale image and the original output image signal; and
a looking up and compensating circuit, electrically coupled to the multiplexer for receiving the original display signal, the looking up and compensating circuit providing a plurality of look-up tables, selecting a specific look-up table from the look-up tables according to the grey-scale luminance of the grey-scale image, and performing a gamma-curve compensating on the original display signal based on the specific look-up table;
wherein, the grey-scale image comprises a plurality of divisions, each one of the divisions corresponds to one of the plurality of grey-scale luminance, and the grey-scale luminance of each one of the divisions is determined according to the grey-scale luminance of another adjacent division of the plurality of divisions.

2. The gamma curve compensating circuit as claimed in claim 1 , further comprising:
a backlight module control circuit, electrically coupled to the multiplexer and controlling a backlight module driving signal for driving a backlight module of the display system according to the grey-scale luminance of the original display signal outputted from the multiplexer.

3. The gamma curve compensating circuit as claimed in claim 1 , wherein the grey-scale insertion determining circuit comprises:
a color space transforming module, transforming the input image signal received by the display system into a color space distributing data;
an analyzing module, electrically coupled to the color space transforming module for receiving the color space distributing data, and analyzing distribution of the color space distributing data to output a corresponding analyzing signal;
a grey-scale insertion limiting module, storing a grey-scale limiting parameter and limiting a varying range of the grey-scale luminance of two adjacent divisions; and
a grey-scale generating module, electrically coupled to the analyzing module and the grey-scale insertion limiting module, determining the grey-scale luminance of the grey-scale image to be inserted according to the analyzing signal and the grey-scale limiting parameter, and outputting the grey-scale image.

4. The gamma curve compensating circuit as claimed in claim 1 , wherein the display system comprises a liquid crystal display.

5. A display system comprising:
a power supply, providing electric power to the display system for operating;
an image receiving terminal, receiving an input image signal;
a gamma curve compensating circuit comprising:
an image generating circuit, generating an original output image signal according to the input image signal;
a grey-scale insertion determining circuit, determining a plurality of grey-scale luminance of a grey-scale image to be inserted according to the input image signal and outputting the grey-scale image;
a multiplexer, having a first input terminal electrically coupled to the grey-scale insertion determining circuit and a second input terminal electrically coupled to the image generating circuit, and the multiplexer being used for selecting one of the grey-scale image and the original output image signal as an original display signal; and
a looking up and compensating circuit, electrically coupled to the multiplexer for receiving the original display signal, the looking up and compensating circuit providing a plurality of look-up tables, selecting a specific look-up table from the look-up tables according to the grey-scale luminance of the grey-scale image, and performing gamma-curve compensation on the original display signal based on the specific look-up table to generate a gamma compensating result; and
a display screen, displaying the gamma compensating result;
wherein the grey-scale image comprises a plurality of divisions, each one of the divisions corresponds to one of the plurality of grey-scale luminance, and the grey-scale luminance of each one of the divisions is determined according to the grey-scale luminance of another adjacent division of the plurality of divisions.

6. The display system as claimed in claim 5 , further comprising:
a backlight module, providing backlight for the display screen.

7. The display system as claimed in claim 6 , further comprising:
a backlight module control circuit, electrically coupled to the multiplexer and controlling a backlight module driving signal for driving a backlight module according to the grey-scale luminance of the grey-scale image outputted from the multiplexer.

8. The display system as claimed in claim 5 , wherein the grey-scale insertion determining circuit comprises:
a color space transforming module, transforming the input image signal received by the display system into a color space distributing data;
an analyzing module, electrically coupled to the color space transforming module for receiving the color space distributing data, and analyzing distribution of the color space distributing data to output a corresponding analyzing signal;
a grey-scale insertion limiting module, storing a grey-scale limiting parameter and limiting a varying range of the grey-scale luminance of two adjacent divisions; and
a grey-scale generating module, electrically coupled to the analyzing module and the grey-scale insertion limiting module, determining the grey-scale luminance of the grey-scale image to be inserted according to the analyzing signal and the grey-scale limiting parameter, and outputting the determined grey-scale image.

9. A gamma curve compensating method, comprising:
selecting a plurality of grey-scales according to a grey-scale limiting parameter and an analyzing signal generated by an input image signal, and generating grey-scale images according to the generated grey-scales;
providing a plurality of look-up tables for the plurality of grey-scales;
selecting a plurality of specific grey-scales from the plurality of grey-scales of an inserted grey-scale image;
generating an original display signal according to the inserted grey-scale image and an original output image generated by the input image;
selecting, from the plurality of look-up tables, a specific look-up table corresponding to the specific grey-scale;
performing a gamma-curve compensation based on the specific look-up table to keep a gamma curve of a related display system invariable in a displaying process; and adjusting a light source of the display system to keep a luminance of the display system invariable in the displaying process;
wherein the grey-scale image comprises a plurality of divisions, each one of the divisions corresponds to one of the plurality of grey-scale luminance, and the grey-scale luminance of each one of the divisions is determined according to the grey-scale luminance of another adjacent division of the plurality of divisions.

10. The gamma curve compensating method as claimed in claim 9 , further comprising:
turning off the light source of the display system in a certain period of time in the displaying process.

11. The gamma curve compensat

Assignees

• Liao Shang-Chia
• Ho Yu-Hsi
• Hsieh Yao-Jen
• Au Optronics Corp

Inventors

• Liao Shang-Chia
• Ho Yu-Hsi
• Hsieh Yao-Jen

Classifications

• G09G3/2011

  by amplitude modulation · CPC title

• G09G3/3611

  Control of matrices with row and column drivers · CPC title

• G09G2320/0673

  for control of gamma adjustment, e.g. selecting another gamma curve · CPC title

• G09G3/3406

  Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336) · CPC title

• G09G5/10 Primary

  Intensity circuits · CPC title