Camera flash for improved color balance

• US 9,681,058 B2
• Filed: 03/20/2012
• Issued: 06/13/2017
• Est. Priority Date: 04/12/2011
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Wang, Qian, Choi, Yun Seok, Tang, Sui Tong, Townsend, Graham Charles
• Primary Examiner(s): Rahman, Mohammad J
• Application Number:
  US13/425,264
• Publication Number:
  US 20120262571A1
• Time in Patent Office: 1,911 Days
• Field of Search: None
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A camera unit and method of control are described. The camera unit has a camera flash sub-unit configurable to emit flash light having an adjustable characteristic. A camera sensor sub-unit generates raw color data when exposed to light for processing into a digital image. The camera unit also includes a camera controller for coordinating operation of the camera flash sub-unit and the camera sensor sub-unit. The camera controller monitors one or more ambient light characteristics in a vicinity of the camera unit. Prior to receiving a command instructing the camera unit to generate the digital image, the camera controller repeatedly configures the camera flash sub-unit based on the monitored ambient light characteristics to adjust the characteristics of the emitted flash light. Once the camera controller receives the command, the camera sensor sub-unit is instructed to expose an image sensor using the pre-adjusted camera flash light to increase illumination.

Claims

1. A method for controlling a camera unit to generate a digital image, the camera unit comprising a camera controller, a camera sensor sub-unit, a camera activation input, and a camera flash sub-unit configured to emit flash light, the method comprising:

in response to receiving, at the camera controller of the camera unit, a first activation signal from the camera activation input, the first activation signal indicative of initiation of the camera unit;

pre-exposing an image sensor of the camera sensor sub-unit to generate pre-image data;

processing, at an image sensor processor of the camera sensor sub-unit, the pre-image data to determine an intensity of the ambient light that is incident on or in a vicinity of the camera unit and to determine a color temperature of the ambient light that is incident on or in the vicinity of the camera unit;

configuring the camera flash sub-unit, using the camera controller, based on the intensity level of the ambient light that is determined to adjust an intensity level of the flash light and based on the color temperature of the ambient light that is determined to adjust a color temperature of the flash light; and

determining, at the camera controller, whether a second activation signal has been received from the camera activation input, the second activation signal indicative of a command for instructing the camera unit to generate the digital image;

absent determining, at the camera controller, that the second activation signal has been received from the camera activation input, repeating pre-exposing, processing, and configuring; and

,

in response to determining, at the camera controller, that the second activation signal has been received from the camera activation input;

controlling the camera-flash sub-unit to cease pre-exposing, processing, and configuring the camera-flash sub-unit;

determining whether to operate the camera-flash unit to emit the flash light to increase illumination;

controlling the camera-flash sub-unit to emit the flash light having the adjusted the intensity level and the adjusted color temperature in response to determining to operate the camera-flash unit during image exposure to increase illumination; and

,

exposing an image sensor of the camera sensor sub-unit to generate raw color data for processing into the digital image.

2. The method of claim 1, wherein processing,

at the image sensor processor of the camera sensor sub-unit, the pre-image data to determine a color temperature of the ambient light that is incident on or in a vicinity of the camera unit comprises:

selecting, at the processor of the image sensor, an algorithm based on the colour temperature of the ambient light that is determined for performing color balancing;

and wherein the method further comprises, after exposing, processing, at the processor of the image sensor, the raw color data using the selected color balancing algorithm.

3. The method of claim 1, wherein for each pre-exposure of the image sensor, processing further comprises:

determining one or more new values based on the pre-image data, each new value being representative of the intensity level of the ambient light; and

updating one or more old values with the one or more new values, each old value being representative of the intensity level of the ambient light for a previous pre-exposure of the image sensor.

4. The method of claim 1, wherein repeating pre-exposing-occurs in real time over a time period occurring prior to receipt of the second activation signal, and wherein repeating configuring comprises configuring the camera flash-sub unit in real time over the time period occurring prior to receipt of the command.

5. The method of claim 1, wherein repeating pre-exposing occurs at discrete intervals over a time period occurring prior to receipt of the second activation signal and wherein repeating configuring comprises configuring the camera flash-sub at each discrete interval over the time period.

6. The method of claim 5, wherein the discrete intervals are substantially equally spaced in time.

7. The method of claim 1, further comprising displaying one or more values on a user interface of the camera unit prior to receiving the second activation signal at the camera controller, each value being representative of the intensity level of ambient light that is detected.

8. The method of claim 7, further comprising receiving input at the user interface to adjust the configuration of the camera flash sub-unit.

19. The method of claim 1, wherein configuring the camera flash sub-unit, using the camera controller, based on the color temperature of the ambient light that is determined, to adjust a color temperature of the flash light further comprises matching the color temperature of the flash light to the color temperature of the ambient light that is determined.

9. A camera unit for generating a digital image, the camera unit comprising:

a camera activation input;

a camera flash sub-unit comprising a plurality of emissive light sources arranged to emit flash light having an adjustable characteristic;

a camera sensor sub-unit comprising an image sensor configured to generate raw color data when exposed and an image sensor processor coupled to the image sensor and configured to process the raw color data generated by the image sensor into the digital image; and

a camera controller coupled to the camera activation input, the camera flash sub-unit and the camera sensor sub-unit for coordinating operation thereof, the camera controller configured to;

in response to receiving a first activation signal from the camera activation input, the first activation signal indicative of initiation of the camera unit;

instruct the camera-sensor sub-unit to perform the steps of;

pre-exposing the image sensor to generate pre-image data; and

processing, using the image sensor processor, the pre-image data to determine the intensity level of the ambient light and to determine a color temperature of the ambient light that is incident on or in a vicinity of the camera unit;

configuring the plurality of emissive sources in the camera flash sub-unit based on the intensity level of the ambient light that is determined to adjust the intensity level of the flash light and based on the color temperature of the ambient light that is determined to adjust a color temperature of the flash light; and

determining whether a second activation signal has been received from the camera activation input, the second activation signal indicative of command for instructing the camera unit to generate the digital image;

absent determining that the second activation signal has been received from the camera activation input, repeating pre-exposing, processing, and configuring;

in response to determining that the second activation signal has been received from the camera activation input;

ceasing pre-exposing, processing, and configuring;

determining whether to operate the camera-flash sub-unit to increase illumination;

instructing the camera-flash sub-unit to emit the flash light having the adjusted intensity level and the adjusted color temperature in response to determining to operate the camera-flash unit to increase illumination; and

,

instructing the camera sensor sub-unit to expose the image sensor to generate raw color data for processing into the digital image.

10. The camera unit of claim 9, wherein processing

using the image sensor processor, the pre-image data to determine, a color temperature of the ambient light that is incident on or in a vicinity of the camera unit comprises:

instructing the image sensor processor to select an algorithm based on the color temperature of the ambient light for performing color balancing; and

wherein the camera controller is further configured to, after exposing, instruct the image sensor processor to process the raw color data using the selected color balancing algorithm.

11. The camera unit of claim 9, wherein for each pre-exposure of the image sensor, processing further comprises:

determining one or more new values based on the pre-image data, each new value being representative of the intensity level of the ambient light; and

updating one or more old values with the one or more new values, each old value being representative of the intensity level of the ambient light for a previous pre-exposure of the image sensor.

12. The camera unit of claim 9, wherein repeating pre-exposing and processing occurs in real time over a time period occurring prior to receipt of the second activation signal to obtain values for the intensity level of the ambient light, and wherein repeating configuring comprises configuring the plurality of emissive sources in the camera flash sub-unit in real time over the time period occurring prior to receipt of the second activation signal.

13. The camera unit of claim 9, wherein repeating pre-exposing and processing occurs at discrete time intervals over a time period occurring prior to receipt of the second activation signal to obtain values for the intensity level of the ambient light, and wherein repeating configuring occurs at the discrete intervals over the time period occurring prior to receipt of the second activation signal.

14. The camera unit of claim 13, wherein the discrete intervals are substantially equally spaced in time.

15. The camera unit of claim 9, further comprising a user interface for displaying one or more values prior to the camera controller receiving the second activation signal, each value being representative of the intensity of ambient light that is incident on or in a vicinity of the camera unit.

16. The camera unit of claim 15, wherein the user interface is configured to receive input to adjust the configuration of the camera flash sub-unit.

17. The camera unit of claim 9, wherein the camera unit is included in a mobile communication device.

20. The camera unit of claim 9, wherein configuring the plurality of emissive sources in the camera flash sub-unit based on the color temperature of the ambient light that is determined to adjust a color temperature of the flash light further comprises matching the color temperature of the flash light to the color temperature of the ambient light that is determined.

18. A non-transitory computer-readable storage medium storing instructions executable by one or more processors coupled to the storage medium, the stored instructions for programming the one or more processors when executed to control a camera unit to generate a digital image, the camera unit comprising a camera flash sub-unit for emitting flash light, a camera activation input, a camera controller, and the stored instructions comprising:

in response to receiving, at the camera controller of the camera unit, a first activation signal from the camera activation input, the first activation signal indicative of initiation of the camera unit;

pre-exposing an image sensor of the camera sensor sub-unit to generate pre-image data;

processing, at an image sensor processor of the camera sensor sub-unit, the pre-image data to determine an intensity of the ambient light that is incident on or in a vicinity of the camera unit and to determine a color temperature of the ambient light that is incident on or in a vicinity of the camera unit;

configuring the camera flash sub-unit, using the camera controller, based on the intensity level of the ambient light that is determined to adjust an intensity level of the flash light and based on the color temperature of the ambient light that is determined to adjust a color temperature of the flash light;

determining, at the camera controller, whether second activation signal has been received from the camera activation input, the second activation signal indicative of a command for instructing the camera unit to generate the digital image;

absent determining, at the camera controller, that the second activation signal has been received from the camera activation input, repeating pre-exposing, processing, and configuring; and

,

in response to determining, at the camera controller, that the second activation signal has been received from the camera activation input;

controlling the camera-flash sub-unit to cease pre-exposing, processing, and configuring

determining whether to operate the camera-flash unit to emit the flash light to increase illumination;

controlling the camera-flash sub-unit to emit the flash light having the adjusted intensity level and the adjusted color temperature in response to determining to operate the camera-flash unit during image exposure to increase illumination; and

,

exposing an image sensor of the camera unit to generate raw color data for processing into the digital image.