ABSTRACT
In Chap. 1 we defined the basic concept of information theory: If H is the average information per unit resolution cell provided by an optical source, and if the source is emitting at a rate of m resolution cells per second, then the rate of information emitted by the optical source is
I = mH bits/sec (3.1)
It is noted that in most of the optical information source there is some degree of temporal and spatial redundancy. To reduce this redundancy it is convenient to replace the original signal (or image) by a different set of new signal elements, that is, optical or image codes. The general procedure for replacing original signals is to perform a certain encoding operation. If the decoding procedure at the receiving end is assumed to be unique, then the encoding and decoding processes will result in no loss of information. However, if the decoding is not a unique process, then some information will be lost. Thus one of the required restrictions on the basic coding theory is a uniquely decodable code.
