  Convolution operation is indispensable in studying analog optical and digital
signal processing. Equally important is the correlation operation. The time
domain community often teaches convolution and correlation only with one
dimensional time signals. That does not clearly demonstrate the effect of
convolution and correlation between two signals. Instead if we consider two
dimensional spatial signals, the convolution and correlation operations can be
very clearly explained. In this paper, we propose a lecture demonstration of
convolution and correlation between two spatial signals using the Fourier
transform tool. Both simulation and optical experiments are possible using a
variety of object transparencies. The demonstration experiments help to clearly
explain the similarity and the difference between convolution and correlation
operations. This method of teaching using simulation and hands-on experiments
can stimulate the curiosity of the students. The feedback of the students, in
my class teaching, has been quite encouraging.
