A method is provided including capturing a frame from a first video device, the frame representing a test pattern and determination is made of at least one captured color for at least one pixel of the captured frame. A reference pixel is provided including at least one reference color, the reference pixel being determined by statistical analysis of the first signals from a population of second video devices that have received the test pattern. A relation is determined between the captured color value and said reference color and the relation is compared with a threshold value. The relation is stored.