1. A method of performing a white balance operation comprising: receiving an image; dividing the image into a plurality of individual subframes; determining whether or not each subframe is substantially monochromatic, wherein the determination is made independently for each individual subframe and is not affected by other subframes in the image, the determining step comprising: obtaining a hue value for each pixel in the subframe, calculating an estimated mean hue for the subframe based on the obtained hue values for a subset of lines at a beginning of the subframe, wherein the subset of lines comprises less than all lines of the subframe, calculating a standard deviation of the hue variances for the subframe using sums of the squares of the differences between the hue value for each pixel in the remaining lines of the subframe not included in the subset of lines and the mean hue, and comparing the standard deviation with a threshold value, wherein the hue value for each pixel in the subframe is used for only one of calculating the estimated mean hue or calculating the standard deviation of the hue variance, such that the determining step occurs in a single pass; and performing a white balance operation on the entire image using hue values only for the subframes which are determined to be not substantially monochromatic to make white balance determinations.