Abstract: An adaptive thresholding technique is calculated by using a real-time 16 pixel running average (RA) 18 to which is added on offset value. The offset value 38 is the product of a programmable factor (alpha) and a Sum Absolute Difference (SAD) noise measurement. The adaptive threshold 42 is compared by a comparator 48 with a delayed analog video signal intensity value on line 46 for the pixel associated with the adaptive threshold. The comparator 48 provides a binary video output for further processing. A relative video output may also be provided by taking the difference of the analog video signal 46 and its corresponding running average 18.

Abstract: A four-quadrant frame of reference, established with respect to a sensed target image, effectively converts the image into a composite target regardable as the union of four, quadrant-based target-segments. Four subgates, each established within a different reference-frame quadrant, become in union a composite tracking gate. As the effectualization of the actual gate-sizing, the degree of conformity between the composite gate and the composite target is then optimized by optimizing the degree of conformity between the subgates and the associated target-segments.