WHITE BALANCE OPTIMIZATION WITH HIGH DYNAMIC RANGE IMAGES

• US 20120262600A1
• Filed: 04/18/2011
• Published: 10/18/2012
• Est. Priority Date: 04/18/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Velarde, Ruben M., Atanassov, Kalin M., Hung, Bob R., Liang, Liang
• Granted Patent: US 8,947,555 B2
• Time in Patent Office: Days
• US Class Current: 348/223.1
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/683 performed by a processor, e.g. controlling the readout of an image memory
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 25/53 Control of the integration time

Abstract

Systems and methods to improve the white balance of a high dynamic range image are disclosed. In a particular embodiment, an imaging device includes a camera sensor and a processor, the processor configured to capture a lighter image and a darker image of a scene. The processor is then configured to white balance the lighter image based on the lighter regions of the image, and to white balance the darker image based on the darker regions of the image. The two images can then be combined to produce a final image.

Claims

1. A method of generating a high dynamic range digital image, comprising:

capturing a first image of a scene from a at least one sensor, wherein the scene has a bright region and a dark region, and wherein the first image is captured using a first exposure setting based on the bright region and wherein the white balance of the first image is determined by the bright region;

capturing a second image of the scene from the at least one sensor, wherein the second image is captured using a second exposure setting based on the dark region, and wherein the white balance of the second image is determined by the dark region; and

generating a high dynamic range digital image by combining the first image and the second image.

2. The method of claim 1, wherein the high dynamic range digital image is generated by combining at least the bright region of the first image with the dark region of the second image.

3. The method of claim 1, wherein the white balance of the first region is also determined based on the first exposure setting or the white balance of the second region is also determined based on the second exposure setting.

4. The method of claim 1, wherein the high dynamic range digital image includes the white balance as applied to the bright region of the first image and the white balance as applied to the dark region of the second image.

5. The method of claim 1, wherein the first exposure setting is determined by:

creating a first luminance histogram of the first image;

determining a threshold from the first luminance histogram; and

determining the bright region based on the threshold.

6. The method of claim 1, wherein the at least one sensor is one sensor.

7. The method of claim 1, wherein the at least one sensor is two sensors, and the first image is captured from a first sensor and the second image is captured from a second sensor.

8. The method of claim 1, wherein the final image is a snapshot.

9. The method of claim 1, wherein the final image is one frame of a video.

10. The method of claim 1, wherein the steps are performed repetitively.

11. An imaging device, comprising:

a camera sensor;

a processor, configured to;

capture a first image of a scene from a at least one sensor, wherein the first image has a bright region and a dark region, and wherein the first image is captured using a first exposure setting based on the bright region and wherein the white balance of the first image is determined by the bright region,

capture a second image of the scene from the at least one camera sensor, wherein the second image is captured using a second exposure setting based on the dark region and wherein the white balance of the second image is determined by the dark region, and

combine the first image and second image to produce a final image; and

a storage for storing the final image.

12. The device of claim 11, wherein the first exposure setting is determined by:

creating a first luminance histogram of the first image;

determining a threshold from the first luminance histogram; and

determining the bright region based on the threshold.

13. The device of claim 11, further comprising:

a second camera sensor, wherein the at least one sensor is two sensors, comprising the first camera sensor and the second camera sensor.

14. The device of claim 11, wherein the final image is a snapshot.

15. The device of claim 11, wherein the processor is configured to perform the steps repetitively.

16. The device of claim 11, wherein the processor is further configured to conditionally determine a white balance of the first region based on the first exposure setting and to conditionally determine a white balance of the second region based on the second exposure setting.

17. A non-transitory computer-readable medium containing processor executable first instructions that are operative to cause a processor to

capture a first image of a scene from a at least one sensor, wherein the first image has a bright region and a dark region, and wherein the first image is

captured using a first exposure setting based on the bright region and wherein the white balance of the first image is determined by the bright region, and

capture a second image of the scene from the at least one sensor, wherein the second image is captured using a second exposure setting based on the dark region and wherein the white balance of the second image is determined by the dark region, and

combine the first image and second image to produce a final image.

18. The computer-readable medium of claim 17, wherein the first exposure setting is determined by:

creating a first luminance histogram of the first image;

identifying a light threshold from the first luminance histogram; and

determining the bright region based on the light threshold.

19. The computer-readable medium of claim 17, also including second instructions operative to cause the processor to execute the first instructions repetitively.

20. An imaging apparatus comprising:

means for capturing a first image of a scene from a at least one sensor, wherein the first image has a bright region and a dark region, and wherein the first image is captured using a first exposure setting based on the bright region and wherein the white balance of the first image is determined, at least in part, by the bright region;

means for capturing a second image of the scene from the at least one sensor, wherein the second image is captured using a second exposure setting based on the dark region, and wherein the white balance of the second image is determined, at least in part, by the dark region; and

means for generating a high dynamic range digital image by combining the first image and second image.