Error Free Coding

An adap~ive ~ransform coding technique followed bya OPCM technique is employed ~o code mul~ispectral data. A method of ins~antaneous expansion of quantization levels by reserving two oodewords in the codebook ~ perform a folding over in quantization is implemented for data with incomplete knowledge of probability density funotion. Controlled redundancy is inserted periodioally as fixed length codewords into the bit strinq of data paoked with variable lenqth codes to facilitate fast retrieval and to detect errors. preliminary results of several sets of data from the ERTS-l data frame and the ERIM· airoraft data frame showed that an error· free reconstruction of the data can be achieved with four bits per picture element or less. 1 The work reported in this paper was sponsored by the National Aeronautics and Space Administration (NASA) under Grant Number NGL 15-005-112 at the Laboratory for Applications of Remote Sensinq (LARS) and under Grant Number NGR 15-005-152. Paper was presented at the 1973 Picture Coding Symposium, January 1973, University of Southern California. 2 J. R. Duan is a graduate student in Electrical Enqineering and P. A. Wintz is Professor of Electrical Enqineerinq, both at Purdue University. • Earth Resources Institute of Michigan. Formerly: University of Michigan/WRL.