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Automatic white balance method and apparatus

一种自动白平衡、白平衡的技术，应用在彩色信号处理电路、彩色电视的零部件、电气元件等方向，能够解决不能修正色温、图像质量劣化等问题

Active Publication Date: 2007-07-04
QUALCOMM INC
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  • Claims
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Problems solved by technology

However, since white balance compensation is dependent on the color temperature of the illuminant, applying a white balance compensation configured for an illuminant at a first color temperature generally does not correct for the color temperature of a second illuminant, and may result in Introduces additional color shift in the image to further degrade the image quality

Method used

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  • Automatic white balance method and apparatus
  • Automatic white balance method and apparatus

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Embodiment Construction

[0019] The gray world assumption may form the basis for implementing white balance in digital photography. It has been observed in a large number of photographs that the average color of the pixel colors in an image is roughly gray. Although there are exceptions depending on the scene, the gray world assumption is very valid and provides a reliable basis for implementing white balance. The automatic white balance (AWB) method and apparatus disclosed in this paper are based on gray world assumption combined with outlier rejection. A digital camera or some other image processing device may be configured to implement the AWB methods described herein.

[0020] The method is described with reference to an image capture device, such as a digital camera. However, it is not necessary for an image capture sensor to be built into the device. Indeed, an electronic device can be configured to implement the AWB method on remotely captured images.

[0021] The digital camera may first d...

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Abstract

Automatic white balance of captured images can be performed based on a gray world assumption. Initially, a flat field gray image is captured for one or more reference illuminations. The statistics of the captured gray image are determined and stored for each reference illumination during a calibration process. For each subsequent captured image, the image is filtered to determine a subset of gray pixels. The gray pixels are further divided into a one or more gray clusters. The average weight of the one or more gray clusters is determined and a distance from the average weights to the reference illuminants is determined. An estimate of the illuminant is determined depending on the distances. White balance gains are applied to the image based on the estimated illuminant.

Description

[0001] Related Application Cross Reference [0002] This application claims rights based on U.S. Provisional Application No. 60 / 583,144, filed June 25, 2004, and entitled "Method and Apparatus for Automatic White Balance," which The US Provisional Application is hereby incorporated by reference in its entirety. technical field [0003] The present invention provides a method and device for performing automatic white balance (AWB), and particularly relates to the technical field of performing automatic white balance on captured images according to a gray world assumption. Background technique [0004] Illumination sources - also referred to herein as illuminants - are usually not pure white, but biased toward a specific color. The color shift is usually measured in color temperature. The human eye compensates for lighting that is not pure white, so colors appear relatively consistent under a wide variety of lighting conditions. However, the electronic sensors used to captu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N9/73H04N1/46H04N1/60
CPCH04N1/6086H04N1/608H04N9/735H04N23/88H04N9/73
Inventor 塞波·洪阿南塔帕德马纳卜汉·A·坎达达伊安德鲁·秦川·丘贝赫纳姆·卡提比安
Owner QUALCOMM INC
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