A comparative critique of two dimensional imagery compression coding - Spatial distance and spatial transform

Two-dimensional transform imagery compression methods are compared with two-dimensional spatial distance compression methods. In particular, a specific code of each class is selected for comparison. Discrete Cosine Transform coding is selected because of its superior performance compared to other transform methods and because of its implementation on several military programs. Spatial distance coding as implemented on the Tactical Digital Facsimile (TDF) is selected as this particular code permits gray scale coding, ease of hardware implementation, and compression/fidelity tradeoff. Spatial distance coding is found to be superior to the Discrete Cosine Transform technique for all block sizes considered up to and including 16 x 16 pixel block size.