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.