Automatic white balance method for color digital image

An automatic white balance and digital image technology, applied in the direction of color signal processing circuit, etc., can solve problems such as image quality degradation, and achieve low complexity and adaptable effects

Inactive Publication Date: 2007-04-04
AVISONIC TECH
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Problems solved by technology

As for the Chikane algorithm, it is based on the concept of pre-processing. Firstly, histogram equalization is applied to the image to improve the contrast of the image pixels, and then a pre-defined critical value is used to determine the reference white point. This method is used for most Satisfactory results can be obtained on the image, but the threshold value is determined in advance and has nothing to do with the state of the image. When the image has a relatively small number of white points, the image quality will deteriorate

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  • Automatic white balance method for color digital image
  • Automatic white balance method for color digital image
  • Automatic white balance method for color digital image

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Embodiment Construction

[0026] According to the present invention, an automatic white balance method applied to a color digital image is to use a dynamic threshold value adapted to the image to determine the white point in the image, and the method includes two steps of white point detection and white point adjustment.

[0027] The flowchart shown in Figure 10 is a YC b C r The embodiment of processing in space, wherein the white point detection is from step 14 to step 24, and the white point adjustment is step 26 and step 28, which are respectively described as follows.

[0028] Step 14: Color Space Conversion

[0029] Convert a color digital image 12, such as captured by an imaging device, from the color space of the three primary colors [RGB] to a luminance-chroma color space [YC] similar to the human visual system b C r ]. In RGB space, color information is red, green and blue color values, in YC b C r In space, the color information is a luminance value and two chroma values. In the techn...

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Abstract

The method comprises: calculating the dynamical threshold fitting the image; selecting the first pixel group satisfying the dynamical threshold as the candidate reference white points; selecting one of the reference white points with higher brightness value as the reference white point; according to the chromatic value of multi colors of the reference white point and the maximum brightness value in the image, getting the gain of multi colors.

Description

technical field [0001] The invention relates to a digital image processing method, in particular to an automatic white balance method applied to color digital images. Background technique [0002] In order to obtain the quality of digital images as under natural light, automatic white balance plays a very important role in the process of digital image processing. Known automatic white balance algorithms include gray world, perfect reflector, fuzzy rules method, Chikane method and so on. Gray world is the most widely used algorithm. It assumes that the average value of the reflection coefficient is a specific gray value. The advantage is that the calculation is simple and satisfactory image quality can be obtained when there are enough color changes in the image. The disadvantage is that it is not easy to determine the gray value, especially if the imagery has large objects of uniform color. The ideal reflector algorithm is based on the assumption that the brightest pixel i...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N9/73
Inventor 翁竟智陈宏铭
Owner AVISONIC TECH
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