Color deviations of images are analyzed using a sensor. The received image sensor signal is analyzed pixel by pixel. An image sensor signal is produced for each color channel from a plurality of color channels. An image sensor signal from a first channel, and one from a second channel, are combined. An output signal of a first color contrast channel is generated. Now an image sensor signal from a third channel is combined with the ones from the first and second image sensors. An output signal of a second color contrast channel is generated. The outputs of these color contrast channels are classified.