FADE DETECTOR FOR DIGITAL VIDEO

Static fade in a digital video image is detected. A difference in luminance intensity is determined for correspondingly positioned pixels in successive images. A variance in the difference is determined, and then normalized according to a mean squared value of the difference to provide a fade index J.sub.n. The fade index is compared to a fade threshold, e.g., 0.9, to determine if a fade is indicated. Optionally, a check may be made to verify that a static fade is indicated by comparing the mean squared value of the difference to a motion threshold. The technique is suitable for both frame mode and field mode video sequences. When the digital images include field mode video, where each image has first and second fields, a fade index is determined separately for each field, and an overall fade index is obtained by averaging the fade indexes from each field. A scheme for detecting static fade on a macroblock by macroblock basis is also presented.