a method of encoding a video sequence including a sequence of video images includes first comparing elements of a portion of a first video image with elements of a portion of a second video image to generate respective intensity difference values for the element comparisons . then , a first value is assigned to the intensity difference values that are above a visually perceptible threshold value and a second value is assigned to the intensity difference values that are at or below the visually perceptible threshold value . next , the method includes summing the first and second values to generate a sum . if the sum is greater than a predetermined decision value , the portion of the first video image is encoded . the method is fully compatible and , thus , may be implemented with video standards such as , for example , h . 261 , h . 263 , motion - jpeg , mpeg - 1 , and mpeg - 2 .