Patent ID: 7826670

Claim:
A data compression apparatus which performs data compression processing for data to be compressed, the data being constituted by a sequence of numeric values indicated by a predetermined unit number of bits, the data compression apparatus comprising: a thinning processing section which creates, by cyclically thinning out a numeric value from the sequence of numeric values constituting the data to be compressed, first data to be compressed which is constituted by a sequence of the numeric values taken out from the data to be compressed by the thinning out, and second data to be compressed which is constituted by a sequence of the remaining numeric values; a lossless compression section which performs lossless compression processing for the first data to be compressed which has been created by the thinning processing section; and a lossy compression section which performs lossy compression processing for the second data to be compressed which has been created by the thinning processing section; and wherein the lossy compression section determines, for the numeric values constituting the second data to be compressed which has been created by the thinning processing section, whether or not the numeric value is between the numeric values before and after the numeric value which have been thinned out by the thinning out of the thinning processing section, outputs a code indicating that the numeric value is between the numeric values before and after the numeric value which have been thinned out if the numeric value is between the numeric values before and after the numeric value which have been thinned out, and outputs a numeric value obtained by re-expressing the numeric value by a smaller number of bits than the unit number of bits if the numeric value is not between the numeric values before and after the numeric value which have been thinned out.