Automatic white balance correction method for image capturing apparatus
Disclosed is an automatic white balance method for image capturing apparatus. An image capturing apparatus captures a color image first and performs gray point searching in RGB color space or YUV color space. The color correction coefficient sets of red color, green color and blue color components of each gray points are computed respectively, and then the color correction coefficient sets of all the gray points are averaged to generate a color correction average value set. Each pixel of the color image is color-corrected in a color space according to the color correction average value set so as to obtain an optimum white balance effect. The present invention is beneficial for the reduction of design cost, downsizing of storage memory space, decrease of computation quantity and simplification of image-searching process.
1. An automatic white balance correction method for an image capturing apparatus, comprising the steps of: capturing a color image by an image capturing apparatus and initiating a gray point searching; computing color correction coefficient sets of each of a first color component, a second color component, and a third color component of each gray points in the color image respectively; avenging color correction coefficient sets of the gray points of the color image and generating a color correction average value set; and performing color correction according to the color correction average value set to each pixel of the color image.
2. The automatic white balance correction method according to claim 1 wherein the gray point searching comprising defining gray points in a RGB color space or a YUV color space.
3. The automatic white balance correction method according to claim 1 wherein each pixel after color correction is comprised of a red color component, a green color component, and a blue color component.
4. The automatic white balance correction method according to claim 1 wherein the luminance of the color image before color correction is identical to the luminance of the color image after color correction.
5. The automatic white balance correction method according to claim 1 wherein the gray points are satisfied with the criteria of: an absolute value of a color difference between the green color component and the blue color component is less than a threshold value, and an absolute value of a color difference between the green color component and the red color component is less than another threshold value.
6. The automatic white balance correction method according to claim 5 wherein the gray points are further satisfied with a criterion of that a green color component value is greater than or equal to a threshold value.
7. The automatic white balance correction method according to claim 3 wherein the gray points are satisfied with the criteria of: an absolute value of a color difference between the red color component and the blue color component is less than a threshold value, and an absolute value of a color difference between the red color component and the green color component is less than another threshold value.
8. The automatic white balance correction method according to claim 7 wherein the gray points are further satisfied with a criterion of that a red color component value is greater than or equal to a threshold value.
9. The automatic white balance correction method according to claim 2 wherein the gray points are satisfied with the criteria of: an absolute value of a chroma red (V) color component is less than a threshold value, and an absolute value of a chroma blue (U) color component is less than another threshold value.
10. The automatic white balance correction method according to claim 9 wherein the gray points are further satisfied with the criterion of that the luminance color (Y) component value is greater than or equal to a threshold value.
11. The automatic white balance correction method according to claim 1 wherein the gray points are satisfied with the criteria of: an absolute value of a color difference between the blue color component and the green component is less than a threshold value, and an absolute value of a color difference between the blue color component and the red color component is less than another threshold value.
12. The automatic white balance correction method according to claim 11 wherein the gray points are further satisfied with a criterion of that a blue color component value is greater than or equal to a threshold value.