A METHOD TO GENERATE A COMPARISON SIGNAL THAT REPRESENTS THE MAGNITUDE DIFFERENCE BETWEEN TWO VIDEO SIGNALS.

摘要

The present invention relates to an apparatus and method for generating a comparison signal representing the magnitude difference between two successive video signals representing adjacent inspection points on the container. The comparison signal is generated with a magnitude representing the ratio between the two video signals. The ratio is calculated with the one of the two video signals having the larger magnitude as the denominator. A comparison signal generated in this manner is insensitive to general light variations across the container.