Detection of colour biases in video images

Due to improper use of television broadcast equipment and/or reference whites in colour video cameras, a colour bias is often introduced into a video image. In excessive amounts, this bias is noticeable and can be annoying to the viewer. An attempt to objectively measure the degree and nature of the colour bias is described. By artificially introducing a colour bias into an existing colour image and constructing a third-order histogram where the histogram is a function of the levels (gray levels) in the red, green, and blue components, certain useful features of the degraded image are obtained. An estimate of the histogram rotation in the three-dimensional colour space is made. This estimate of the rotation, expressed as a real-valued number, is a measurement of the colour bias in the image