A microprocessor-based electronic system has been designed to detect t
he position of a black/white transition line viewed by a conventional
closed circuit television monochrome camera. The system examines the v
ideo signal for sharp changes in level, corresponding to sudden change
s in brightness, and generates a digital output. The detection circuit
ry works at video rates. The system has been used with the principle o
f optical sectioning to profile a variety of surfaces, and some prelim
inary results are presented.