System and method for nested split coding of sparse data sets

Abstract

A data encoder and method successively analyzes successively smaller blocks of a specified data array. Data blocks are analyzed in a predefined order, and corresponding entries identifying data blocks containing at least one non-zero value are stored in that same order in a list of blocks. Whenever a data block is processed, if the data block is entirely filled with zero data it is so identified in the output data and no further processing of the subblock is required. Otherwise, if the size of the data block is greater than a predefined minimum block size (e.g., 2.times.2), the block is divided into smaller data blocks and those smaller data blocks are put on the list of blocks for further processing. Finally, if the size of a data block that is being processed is the predefined minimum block size, values representing all the data items in that data block are written into the output data. Information identifying the number of bits required to encode the maximum data value in each data block is written into the output data in the same order that the blocks are analyzed, thereby enabling a decoder procedure to determine the number of data bits used to encode each data value stored in the output data. A data decoder and method retraces the encoded data so as to reverse the process performed by the encoding method. The encoder and decoder can be implemented in either hardwired logic or computer software.