Method for white balance adjustment
A white balance adjustment method includes capturing a raw image where an arrangement format of the raw image is BGb/GrR, extracting color scale values of each color channels, and obtaining cumulative proportion of color scale values in each channel. Cumulative proportion of each channels are compared with default minimum and maximum values, to get a cumulative proportion which is above a maximum value treated as a reference white, and a cumulative proportion below the minimum value treated as a reference black. The color scale values are re-quantized according to the obtained reference white and black, by using a color histogram equalization method.
1. A white balance adjustment method for processing a color digital image, the method comprising:
S 1 : capturing a raw image using an electronic device;
S 2 : an arrangement format of pixels of the raw image is BGb/GrR;
S 3 : extracting each B, Gb, Gr, and R channels from the raw image, and obtaining color scale values of all pixels corresponding to each channels;
S 4 : separately scanning the color scale values of all pixels in B, Gb, Gr, and R channels, and recording a number of pixels corresponding to each color scale values, and obtaining cumulative proportion of each color scale values in B, Gb, Gr, and R channels;
S 5 : comparing the cumulative proportion of each B, Gb, Gr, and R channels with a default minimum value and a maximum value, to get a cumulative proportion which is greater than or equal to the maximum value and a cumulative proportion which is less than or equal to the minimum value, the cumulative proportion which is greater than or equal to the maximum value corresponding to an average value of the color scale values is a reference white; the cumulative proportion which is less than or equal to the minimum value corresponding to an average value of the color scale values is a reference black; and
S 6 : re-quantizing the color scale values of each B, Gb, Gr, and R channels, according to the reference white and the reference black, by using a color histogram equalization (CHE) method.
2. The white balance adjustment method as claimed in claim 1 , wherein the minimum value is 0.01, the maximum value is 0.99.
3. The white balance adjustment method as claimed in claim 1 , wherein a range of the color scale values of all pixel is [0, 2 n −1], where “n” is a number of bits of the pixel.
4. The white balance adjustment method as claimed in claim 1 , wherein the re-quantized color scale value by using the color histogram equalization (CHE) method is
C
-
L
(
2
n
-
1
)
-
L
(
2
n
-
1
)
,
where “C” is the color scale values corresponding to the cumulative proportions of B, Gb, Gr, and R channels which are located between the maximum value and the minimum value, “L” is the color scale value corresponding to the reference black, “n” is a number of bits of the pixel.