Method and apparatus to synchronize backlight intensity changes with image luminance changes

• US 20060001641A1
• Filed: 06/30/2004
• Published: 01/05/2006
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wyatt, David, Degwekar, Anil A.
• Granted Patent: US 8,358,262 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• 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 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• 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 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

An approach for coordinating backlight intensity and image luminance changes. For one aspect, in response to determining that a display-related event has occurred during a vertical frame period indicating a subsequent change associated with at least one of a backlight intensity and a frame buffer palette is to be undertaken, an interrupt is enabled. During subsequent interrupt processing, associated changes to the backlight intensity and the frame buffer palette are applied in a coordinated manner. For a specific implementation, an approach is provided for a graphics controller driver to synchronize response to changes in display backlight, color-space controls, and in the luminance of images, wherein said changes can come from different sources, occur at a different rates, and have different latencies, for the purpose of applying graphics settings responses such that those effects occur at a visually co-incident interval so as to substantially minimize discordant visual artifacts.

Claims

1. A method comprising:

in response to determining that a display-related event has occurred during a vertical frame period indicating that an associated change to at least one of a backlight intensity and an image luminance are to be undertaken, enabling an interrupt; and

during subsequent interrupt processing, applying corresponding changes to the backlight intensity and the image luminance in a coordinated manner.

2. The method of claim 1 wherein applying changes to the backlight intensity and the image luminance in a coordinated manner includes

applying a backlight intensity change, and

decrementing a delay counter based on a predetermined delay to determine when to apply a change to the image luminance.

3. The method of claim 1 further comprising

determining that the display-related event has occurred during the vertical frame period by checking at least a first dirty flag.

4. The method of claim 3 wherein checking the at least first dirty flag includes checking a histogram dirty flag, a backlight dirty flag and a gamma dirty flag.

5. The method of claim 4 further comprising:

setting a histogram dirty flag in response to detecting a change in average image intensity,

setting a backlight dirty flag in response to a request to adjust a backlight setting, and

setting a gamma dirty flag in response to a request to change a gamma look-up table.

6. The method of claim 5 wherein

setting a histogram dirty flag in response to detecting the change in average image intensity includes setting the histogram dirty flag only if the detected change is larger than or equal to a predetermined trigger point.

7. A method comprising:

enabling an interrupt if at least a first display-related dirty flag has been set during a vertical frame period; and

in response to the interrupt, applying associated changes to a backlight intensity and an image luminance in a coordinated manner.

8. The method of claim 7 wherein

enabling an interrupt if at least a first display-related dirty flag has been set includes enabling an interrupt if one of a histogram, a backlight and a gamma dirty flat has been set during the vertical frame period.

9. The method of claim 8 further comprising

setting a histogram dirty flag in response to detecting a change in average image intensity larger than or equal to a threshold change;

setting a backlight dirty flag in response to receiving a request to change the backlight intensity; and

setting a gamma dirty flag in response to receiving a request to change the image luminance.

10. The method of claim 9 further comprising

receiving a request to change at least one of the backlight intensity and the image luminance from at least one of an input device, an operating system, a software module and an application program.

11. The method of claim 9 wherein

detecting a change in average image intensity larger than or equal to a threshold change includes comparing an average image intensity of a current frame to an average image intensity of a previous frame.

12. The method of claim 11 further comprising

computing a histogram for each frame, and

determining an average image intensity for each frame based on the respective histogram.

13. The method of claim 7 wherein applying associated changes to the backlight intensity and the image luminance in a coordinated manner includes

applying the change to the backlight intensity, and

applying the change to the image luminance after a delay such that the change to the image luminance and the change to the backlight intensity take effect at substantially a same time.

14. The method of claim 13 further comprising

initiating a delay count, and

wherein applying the change to the image luminance occurs in response to completion of the delay count.

15. A method comprising:

in response to an interrupt being asserted and determining that a display-related dirty flag is set, calculating new values for a backlight intensity and a gamma look-up table;

applying associated changes to the backlight;

initiating a delay count; and

applying associated changes to the gamma look-up table upon expiration of the delay count.

16. The method of claim 15 further comprising:

using a deferred procedure call to perform at least one of calculating the new values, applying the associated changes to the backlight, initiating the delay count and applying associated changes to the gamma look-up table.

17. The method of claim 15 wherein

initiating the delay count includes initiating a delay count based on the new value for the backlight intensity and a latency associated with changing the backlight intensity to the new value.

18. A computer-accessible medium storing information that, when accessed by a computer, causes the computer to

in response to determining that a display-related event has occurred during a vertical frame period indicating that an associated change to at least one of a backlight intensity and an image luminance are to be undertaken, enable an interrupt;

and

during subsequent interrupt processing, apply corresponding changes to the backlight intensity and the image luminance in a coordinated manner.

19. The computer-accessible medium of claim 18 wherein applying changes to the backlight intensity and the image luminance in a coordinated manner includes

applying a backlight intensity change, and

decrementing a delay counter based on a predetermined delay to determine when to apply a change to the image luminance.

20. The computer-accessible medium of claim 18 further storing information that, when accessed by the computer causes the computer to

determine that the display-related event has occurred during the vertical frame period by checking at least a first dirty flag.

21. The computer-accessible medium of claim 20 wherein checking the at least first dirty flag includes checking at least one of a histogram dirty flag, a backlight dirty flag and a gamma dirty flag.

22. The computer-accessible medium of claim 21 further storing information that, when accessed by the computer causes the computer to:

set a histogram dirty flag in response to detecting a change in average image intensity,

set a backlight dirty flag in response to a request to adjust a backlight setting, and

set a gamma dirty flag in response to a request to change a gamma look-up table.

23. The computer-accessible medium of claim 22, wherein

setting a histogram dirty flag in response to detecting the change in average image intensity includes setting the histogram dirty flag only if the detected change is larger than or equal to a predetermined trigger point.

24. A system comprising:

a bus;

a processor coupled to the bus to execute instructions;

a display coupled to the processor;

an antenna coupled to receive information for the processor over a wireless interconnect; and

a memory coupled to the processor to store instructions that, when executed by the processor, cause the processor to

enable an interrupt in response to detecting a display-related event; and

apply changes to a display backlight setting and an image luminance associated with the display-related event in a coordinated manner such that the changes take effect at substantially a same time.

25. The system of claim 24 wherein the memory further stores instructions that, when executed by the processor, cause the processor to

detect the display-related event by checking at least one of a backlight, gamma and histogram dirty flag.

26. The system of claim 24 wherein applying changes to the display backlight and the image luminance in a coordinated manner includes

applying the change to the display backlight setting;

and

applying the change to the image luminance after a predetermined delay based at least in part on a latency associated with applying the change to the display backlight setting.

27. The system of claim 24 wherein the instructions comprise a display driver.