Display apparatus of adjusting gamma and brightness based on ambient light and its display adjustment method

• US 20090237423A1
• Filed: 03/20/2008
• Published: 09/24/2009
• Est. Priority Date: 03/20/2008
• Status: Abandoned Application

• Current Assignee: Capella Microsystems, Corp.
• Original Assignee: Capella Microsystems, Corp.
• Inventors: Tsang, Koon Wing, Shih, Cheng-Chung
• Application Number:
  US12/076,572
• Publication Number:
  US 20090237423A1
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• 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 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

This invention discloses a display apparatus capable of adjusting gamma and brightness based on ambient light and its display adjustment method. The display apparatus is adjusted to display an image output signal based on an image input signal and the correlated color temperature and brightness of an ambient light. The display apparatus includes a plurality of light sensing circuits, a memory unit, an image processing module, and a display module. The light sensing circuit senses the ambient light to produce a digital ambient color temperature index value. The memory unit stores a lookup table of brightness expression rates and gamma adjustment parameters corresponding to different color temperature index values. The image processing module produces a gamma adjustment parameter by a lookup table based on the color temperature index value and generates the gamma expression rate of the image input signal. The image processing module adjusts the image input signal to generate the image output signal based on the gamma adjustment parameter. The display module displays the image output signal.

Claims

1. A display apparatus of adjusting gamma and brightness based on an ambient light, for receiving and displaying an image input signal, and the display apparatus comprising:

a plurality of light sensing circuits for sensing at least two color light brightness of the ambient light to generate a plurality of light brightness signals respectively;

a memory unit for storing a lookup table, and the lookup table providing a plurality of gamma coefficient and a plurality of gamma adjustment parameters corresponding to different ambient light correlated temperature conditions;

an image processing module for receiving the image input signal from any image sources, and coupled to the light sensing circuits to receive the light brightness signals respectively, and executes a numeric operation of the light brightness signals to generate an ambient color temperature index value, and the image processing module being coupled to the memory unit to process the image input signal by using the lookup table, and the image processing module obtaining a gamma correction adjustment parameter by using the lookup table based on the ambient color temperature index value and generating the gamma correction expression rate of the image input signal, and the image processing module adjusting a gamma correction expression rate of the image input signal based on the gamma correction adjustment parameter to generate an image output signal; and

a display module coupled to the image processing module, and for displaying the image output signal.

2. The display apparatus of claim 1, wherein the plurality of light sensing circuits include a red light sensing circuit, a green light sensing circuit and a blue light sensing circuit, and the red light sensing circuit is used for sensing a red light brightness of the ambient light to generate a red light brightness signal, and the green light sensing circuit is used for sensing a green light brightness of the ambient light to generate a green light brightness signal, and the blue light sensing circuit is used for sensing a blue light brightness of the ambient light to generate a blue light brightness signal.

3. The display apparatus of claim 1, further comprising a backlight module coupled to the image processing module to provide a backlight brightness required by the display module.

4. The display apparatus of claim 3, wherein the image processing module comprises:

a gamma processing unit for executing numeric calculations of the red light brightness signal, the green light brightness signal and the blue light brightness signal to produce the ambient color temperature index value; and

a brightness processing unit for executing numeric calculations of the red light brightness signal, the green light brightness signal and the blue light brightness signal to produce the brightness value.

5. The display apparatus of claim 4, wherein the memory unit stores a first lookup table, and the first lookup table provides a plurality of brightness expression rates and a plurality of backlight brightness adjustment parameters corresponding to different brightness values, and each backlight adjustment parameters corresponds to one of the brightness expression rates.

6. The display apparatus of claim 1, wherein the image processing module obtains a gamma correction adjustment parameter by using a second lookup table based on the ambient color temperature index value and generate the gamma expression rate of the image input signal, and the image processing module adjusts a gamma correction expression rate of the image input signal based on the gamma correction adjustment parameter.

7. The display apparatus of claim 2, wherein the blue light brightness signal is multiplied with a first parameter to generate a first multiplied result, and then the multiplied result is subtracted by the red light brightness signal, and the subtracted result is divided by the green light brightness signal to generate the ambient color temperature index value.

8. The display apparatus of claim 4, wherein the ambient color temperature index value is multiplied with a gain parameter to generate a second multiplied result, and the second multiplied result is added by an offset parameter to generate the gamma correction adjustment parameter.

9. The display apparatus of claim 5, wherein the memory unit stores a third lookup table, and the third lookup table provides a lookup table of a plurality of contrast expression rates and a plurality of contrast adjustment parameters corresponding to different brightness values, and each contrast adjustment parameters corresponds to one of the contrast expression rates.

10. The display apparatus of claim 1, wherein the image processing module further provides a contrast adjustment parameter by using the third lookup table based on the brightness value and the contrast expression rate of the image input signal, and the image processing module adjusts the contrast expression rate of the image input signal based on the contrast adjustment parameter to generate the image output signal.

11. The display apparatus of claim 1, further comprising:

a brightness sensing module for sensing a brightness of the display module at different positions or different directions to generate a plurality of brightness signals;

a brightness distribution processing circuit coupled to the brightness sensing module, and for generating a distribution signal based on the brightness signal;

a backlight module for providing a backlight brightness required by the display module;

a pulse width modulation (PWM) generation circuit for generating a pulse width modulation signal; and

a plurality of duty cycle modulation units separately coupled to the pulse width modulation generation circuit to receive the pulse width modulation signal.

12. The display apparatus of claim 11, wherein the image processing module obtains an original backlight adjustment parameter by using the second lookup table based on the brightness value and the brightness expression rate of the image input signal, and the image processing module produces a plurality of backlight adjustment parameters based on the original backlight adjustment parameter together with the distribution signal, and the backlight adjustment parameters are inputted separately to the duty cycle modulation units, and the duty cycle modulation units separately adjust the duty cycle of the pulse width modulation signal to generate a plurality of backlight brightness driving signals based on the backlight adjustment parameters, and the backlight brightness driving signals are used for driving the backlight module to produce a required backlight brightness distribution.

13. A gamma and brightness adjustment method applied in a display apparatus, and the gamma and brightness adjustment method comprising:

setting a second lookup table to provide a lookup table of a plurality of gamma correction adjustment parameters corresponding to different digital color temperature index values;

sensing an ambient correlated temperature value of the ambient light;

executing a signal analysis of the image input signal to produce a gamma correction expression rate;

obtaining a gamma correction adjustment parameter from the second lookup table based on the ambient color temperature index value and generates the gamma correction expression rate required by the image input signal; and

using the gamma correction adjustment parameter to adjust the gamma correction expression rate of the image input signal to generate the image output signal.

14. The gamma and brightness adjustment method of claim 13, wherein the gamma correction adjustment parameter obtained from the second lookup table based on the ambient color temperature index value and the desired displaying gamma correction expression rate of the image input signal is generated from the gamma correction value and the gamma correction expression rate of the image input signal together with the data of the second lookup table to execute a signal process to produce the gamma correction adjustment parameter.

15. The gamma and brightness adjustment method of claim 13, further comprising:

setting a first lookup table to provide a lookup table of a plurality of brightness expression rates and a plurality of backlight brightness adjustment parameters corresponding to different brightness values;

sensing a brightness value of the ambient light;

executing a signal analysis of the image input signal to produce a brightness expression rate;

obtaining a backlight adjustment parameter from the first lookup table based on the brightness value and the brightness expression rate of the image input signal; and

using the backlight adjustment parameter to adjust a backlight brightness of the display apparatus.

16. The gamma and brightness adjustment method of claim 13, further comprising:

setting a third lookup table to provide a lookup table of a plurality of contrast expression rates and a plurality of contrast adjustment parameters corresponding to different brightness values;

sensing a brightness value of the ambient light;

executing a signal analysis of the image input signal to generate a contrast expression rate;

obtaining a contrast adjustment parameter from the third lookup table based on the color temperature index value and the contrast expression rate of the image input signal; and

using the contrast adjustment parameter to adjust a contrast expression rate of the image input signal to generate the image output signal.

17. The gamma and brightness adjustment method of claim 13, further comprising:

setting a first lookup table for providing a lookup table of a plurality of brightness expression rates and a plurality of backlight adjustment parameters corresponding to different brightness values;

sensing a brightness value and an ambient light distribution value of the ambient light;

executing a signal analysis of the ambient light distribution value to generate a distribution signal;

executing a signal analysis of the image input signal to produce a brightness expression rate;

obtaining an original backlight adjustment parameter from the first lookup table based on the brightness value and the brightness expression rate;

integrating the original backlight adjustment parameter and the digital distribution signal to generate a plurality of backlight brightness driving signals; and

using the backlight brightness driving signals to produce a desired backlight brightness distribution.