Method and Apparatus for Controlling a Camera Module to Compensate for the Light Level of a White LED

• US 20080180544A1
• Filed: 01/25/2007
• Published: 07/31/2008
• Est. Priority Date: 01/25/2007
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Wu, Ken, Drader, Marc, Purdy, Michael
• Granted Patent: US 7,825,958 B2
• Time in Patent Office: Days
• US Class Current: 348/223.1
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0567 Solid-state light source, e.g. LED, laser
• CPC Class Codes: H04N 23/56 provided with illuminating means
• 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

Abstract

A method and an apparatus enabling use of a light source emitting a light of changing intensity and changing spectrum as a flash with a camera module having a white-balance routine and an exposure routine, wherein an initial value representative of a color spectrum emitted by the light source is transmitted to the camera module, the light source is turned on, and the camera module is signaled to scan a plurality of images of the scene while the light source is turned on, allowing the white-balance and exposure algorithms to be employed with each image scanned to refine the first initial value to refine the degree of compensation employed in correcting a color and a light level in the last one of the images of the plurality of images scanned.

Claims

1. A method of enabling use of a camera module with a light source to take a picture of a scene, the camera module having a white-balance routine, the light source serving as a flash and emitting a light of changing spectrum when operated, the method comprising:

transmitting to the camera module a value representative of a color spectrum capable of being emitted by the light source;

operating the light source to emit light;

performing a plurality of times a loop comprising;

scanning an image;

executing the white-balance routine on the image to derive a processed image; and

employing the value in the executing of the white-balance routine to refine the value for use in a subsequent performance of the loop; and

employing one of the processed images as the picture.

2. The method of claim 1, further comprising employing as the light source a LED that emits a combination of yellow light and blue light approximating white light.

3. The method of claim 1, further comprising employing as the light source a blue LED to which red and green phosphors have been added.

4. The method of claim 1, further comprising transmitting another value representative of a level of light available at the scene absent the light source to the camera module, and wherein the loop further comprises executing an exposure routine of the camera module on the image to derive the processed image and employing the another value in the executing of the exposure routine to refine the another value for use in a subsequent performance of the loop.

5. The method of claim 1, further comprising causing the camera module to cease performing the loop in response to scanning a predetermined quantity of images.

6. The method of claim 1, further comprising causing the camera module to cease performing the loop in response to the degree to which an execution of the white-balance routine refines the value being reduced to a predetermined threshold.

7. An electronic device capable of taking a picture of a scene, the electronic device comprising:

a light source emitting a light of changing intensity and changing spectrum structured to be used as a flash;

a camera module having a white-balance routine and an exposure routine;

a processor capable of controlling the light source and capable of communicating with the camera module; and

a first storage having stored therein a control program comprising a sequence of instructions that when executed by the processor causes the processor to;

transmit a first initial value representative of a color spectrum emitted by the light source to the camera module;

turn on the light source; and

signal the camera module to scan a plurality of images of the scene, causing the camera module to execute the white-balance routine and the exposure routine with the scan of each image of the plurality of images to refine the first initial value to refine the degree of compensation employed in correcting a color and a light level in the last one of the images of the plurality of images scanned.

8. The electronic device of claim 7, wherein the light source is a LED emitting a combination of yellow light and blue light approximating white light.

9. The electronic device of claim 7, wherein the camera module provides a scanned image to the processor without storing the scanned image in a frame buffer.

10. The electronic device of claim 7, wherein the white-balance routine implements an algorithm selected from a group consisting of a white world algorithm and a gray world algorithm.

11. The electronic device of claim 7, further comprising an input device operable by a user of the electronic device to select between using the light source to take a picture of a scene and using light available at the scene to take a picture of the scene, and wherein the sequence of instructions further causes the processor to refrain from transmitting the first initial value to the camera and to transmit a second initial value to the camera representative of a color spectrum emitted by another light source.

12. The electronic device of claim 7, wherein the sequence of instructions further causes the processor to transmit a second initial value representative of a level of light available at the scene absent the light source to the camera module.