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

• US 8,358,262 B2
• Filed: 06/30/2004
• Issued: 01/22/2013
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Wyatt, David, Degwekar, Anil A.
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US10/882,446
• Publication Number:
  US 20060001641A1
• Time in Patent Office: 3,128 Days
• Field of Search: 345/102, 345 97- 98, 345/207
• 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:

determining that a display-related event has occurred during a vertical frame period by determining whether an average image intensity has changed, whether a backlight setting has changed, and whether a gamma look-up table has changed;

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;

in response to determining that the 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 by initiating changes to the backlight intensity and, after a delay based on an amount of time it takes for the backlight intensity to reach a target level, applying changes to the image luminance.

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 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.

4. A method comprising:

enabling an interrupt if one or more of an average image intensity, a backlight setting, or a gamma look-up table has changed during a vertical frame period;

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; and

in response to the interrupt, applying associated changes to a backlight intensity and an image luminance in a coordinated manner by initiating changes to the backlight intensity and, after a delay based on an amount of time it takes for the backlight intensity to reach a target level, applying changes to the image luminance.

5. The method of claim 4 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.

6. The method of claim 4 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.

7. The method of claim 6 further comprising

computing a histogram for each frame, and

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

8. The method of claim 4 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.

9. The method of claim 8 further comprising

initiating a delay count, and

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

10. An article comprising a non-transitory computer-accessible medium storing a plurality of instructions that in response to being executed by a processor, cause the processor to:

determine that a display-related event has occurred during a vertical frame period by determining whether an average image intensity has changed, whether a backlight setting has changed, and whether a gamma look-up table has changed;

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;

in response to determining that the 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 by initiating changes to the backlight intensity and, after a delay based on an amount of time it takes for the backlight intensity to reach a target level, applying changes to the image luminance.

11. The article of claim 10 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.

12. The article of claim 10, 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.