Television picture transmission and optical signal processing

Optical signal processing is introduced as a tool for investigations in the field of television compression research. An optical signal processing system is designed, which performs the Fourier transform of a picture signal F[B(x,y)] and its reconstruction F⁻¹ {F [B(x,y)]} . Some basic optical filtering experiments are performed in the spatial frequency plane, and the optical analogue of the frequency sampling theorem is demonstrated. The Fourier transforms of test pattern pictures show large gaps which can be used for compression. Observation of complex spectra of continuous tone pictures is found to be impaired by noise effects. A physiological experiment is carried out, which investigates the relationship between tolerable flicker frequency and spatial frequency of a television picture. It is found that the tolerable flicker rate f decreases as the spatial frequency fx is increased, according to the empirical equation fc = fo exp(-kfx). fo and k are parameters depending on factors like contrast ratio, kind and size of picture, etc. Compression systems using the above results are found to have a limit of obtainable compression ratio of approximately 3 to 1.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat