REDUCE OPERATING ENVIRONMENT EFFECT USING MULTIPLE CAMERAS

• US 20140211041A1
• Filed: 01/25/2013
• Published: 07/31/2014
• Est. Priority Date: 01/25/2013
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: HONG, Sung Ho, MCCRACKIN, Laura
• Granted Patent: US 9,247,223 B2
• Time in Patent Office: Days
• US Class Current: 348/223.1
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/286 having separate monoscopic and stereoscopic modes
• CPC Class Codes: H04N 13/30 Image reproducers optical systems for producing stereoscopic or other three-dimensional effects G02B30/00
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/661 Transmitting camera control signals through networks, e.g. control via the Internet
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• 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

Methods and devices for automatically white balancing an image are described. In one embodiment, a method includes: capturing a first image using a first camera associated with an electronic device and capturing a second image using a second camera associated with the electronic device, the first image and the second image being temporally related; determining one or more white balance correction values for the first image by analyzing the first image and the second image, the white balance correction value representing the effect of lighting conditions on the first image and the second image; and correcting one or more images captured by the first camera based on the white balance correction value.

Claims

1. A method of automatically white balancing an image, the method comprising:

capturing a first image using a first camera associated with an electronic device and capturing a second image using a second camera associated with the electronic device, the first image and the second image being temporally related;

determining one or more white balance correction values for the first image by analyzing the first image and the second image, the white balance correction value representing the effect of lighting conditions on the first image and the second image; and

correcting one or more images captured by the first camera based on the white balance correction value.

2. The method of claim 1, wherein correcting one or more images captured by the first camera based on the white balance correction value comprises:

correcting the first image.

3. The method of claim 1, wherein determining one or more white balance correction value for the first image by analyzing the first image and the second image comprises:

performing a multi-image analysis by analyzing pixels of the first image and the second image to obtain the one or more white balance correction values, the one or more white balance correction values providing a collective measure of the degree to which both the first image and the second image require correction for the effect of lighting conditions.

4. The method of claim 1, further comprising, prior to capturing the first image using the first camera and prior to capturing the second image using the second camera:

providing, on the electronic device, a selectable operating mode for capturing a two dimensional image using the first camera,

and wherein the first image and the second image are captured when the electronic device is in the operating mode for capturing the two dimensional image using the first camera.

5. The method of claim 4, further comprising, after determining the one or more white balance correction values:

discarding the second image.

6. The method of claim 4, wherein the first camera and the second camera are oriented to obtain images of subjects at a common side of the electronic device and wherein the first camera and the second camera are disposed in spaced relation to one another, the method further comprising:

providing a selectable operating mode on the electronic device for obtaining stereoscopic data using the first camera and the second camera.

7. The method of claim 1, wherein determining one or more white balance correction values for the first image by analyzing the first image and the second image comprises:

identifying a region of one of the first image or the second images that is lighter than any other regions of the first image and the second image; and

determining the one or more of the white balance correction values based on the colour in the identified region.

8. The method of claim 1 wherein determining one or more white balance correction values for the first image by analyzing the first image and the second image comprises:

obtaining an average measure of colour across both the first image and the second image; and

determining the one or more white balance correction values based on the difference between the average measure of colour and middle gray.

9. The method of claim 1, wherein the first camera is a rear-facing camera and the second camera is a front-facing camera.

10. The method of claim 1, further comprising, prior to correcting:

determining that the first camera and the second camera are subject to comparable lighting conditions.

11. The method of claim 10, wherein determining that the first camera and the second camera are subject to comparable lighting conditions comprises:

comparing the exposure time associated with the first camera and the exposure time associated with the second camera.

12. The method of claim 1, further comprising:

determining that the first camera and the second camera are not subject to comparable lighting conditions; and

when the first camera and the second camera are not subject to comparable lighting conditions, performing white balancing on one or more images captured with the first camera by analyzing the first image and not the second image.

13. The method of claim 1, further comprising:

providing a selectable operating mode on the electronic device for capturing a two dimensional image using the first camera; and

when the electronic device is operating in the operating mode for capturing a two dimensional image using the first camera, using the second camera to detect the presence of a flicker source.

14. The method of claim 13, wherein using the second camera to detect the presence of a flicker source comprises:

adjusting an exposure time for the second camera to a value incompatible with a local mains frequency;

after adjusting the exposure time, capturing the second image at the second camera;

analyzing the second image to identify an effect associated with the presence of flicker; and

when the second image is found to contain the effect associated with the presence of flicker, determining that a flicker source is present.

15. The method of claim 13, further comprising:

when a flicker source is detected, restricting an exposure time setting associated with the first camera to values compatible with a local mains frequency; and

when a flicker source is not detected, allowing an exposure time setting associated with the first camera to be set to values incompatible with the local mains frequency.

16. An electronic device comprising:

a first camera;

a second camera; and

a processor connected to the first camera and the second camera, the processor configured to;

capture a first image using the first camera and capture a second image using the second camera, the first image and the second image being temporally related;

determine one or more white balance correction values for the first image by analyzing the first image and the second image, the white balance correction value representing the effect of lighting conditions on the first image and the second image; and

correct one or more images captured by the first camera based on the white balance correction value.

17. The electronic device of claim 16, wherein correcting one or more images captured by the first camera based on the white balance correction values comprises:

correcting the first image.

18. The electronic device of claim 16, wherein determining one or more white balance correction values for the first image by analyzing the first image and the second image comprises:

performing a multi-image analysis by analyzing pixels of the first image and the second image to obtain the one or more white balance correction values, the one or more white balance correction values providing a collective measure of the degree to which both the first image and the second image require correction for the effect of lighting conditions.

19. The electronic device of claim 16, wherein the processor is further configured to, prior to capturing the first image using the first camera and prior to capturing the second image using the second camera:

provide, on the electronic device, a selectable operating mode for capturing a two dimensional image using the first camera,

and wherein the first image and the second image are captured when the electronic device is in the operating mode for capturing the two dimensional image using the first camera.

20. A method for detecting the presence of a flicker source at an electronic device, the method comprising:

providing a selectable operating mode on the electronic device for capturing a two dimensional image using a first camera; and

when the electronic device is operating in the operating mode for capturing a two dimensional image using the first camera, using a second camera to detect the presence of a flicker source.