Reduce operating environment effect using multiple cameras

Patent metadata

Field	Value
Publication number	US-9247223-B2
Application number	US-201313749800-A
Country	US
Kind code	B2
Filing date	Jan 25, 2013
Priority date	Jan 25, 2013
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

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.

First claim

The invention claimed is:

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,
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 and wherein the pixels of the first image and the pixels of the second image are attributed different weights in the multi-image analysis.

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 , 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.

4. The method of claim 3 , further comprising, after determining the one or more white balance correction values:
discarding the second image.

5. The method of claim 3 , 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.

6. 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.

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:
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.

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

9. 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.

10. The method of claim 9 , 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.

11. 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.

12. 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.

13. The method of claim 12 , 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.

14. The method of claim 12 , 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.

15. 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,

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 and wherein the pixels of the first image and the pixels of the second image are attributed different weights in the multi-image analysis.

16. The electronic device of claim 15 , wherein correcting one or more images captured by the first camera based on the white balance correction values comprises: correcting the first image.

17. The electronic device of claim 15 , 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.

18. A non-transitory computer-readable medium comprising computer-executable instructions for performing a 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

Assignees

• Research In Motion Ltd
• Blackberry Ltd

Inventors

• Mccrackin Laura
• Hong Sung Ho

Classifications

• H04N23/67

  Focus control based on electronic image sensor signals · CPC title

• H04N23/45

  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 title

• H04N23/88 Primary

  for colour balance, e.g. white-balance circuits or colour temperature control · CPC title

• H04N23/611

  where the recognised objects include parts of the human body · CPC title

• H04N23/667

  Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes · CPC title