Method, apparatus and recording medium for data compression

A data compression apparatus for obtaining compressed coded data by quantization of original data to obtain quantized data followed by coding and compression of the quantized data, the data compression apparatus comprising:

• classification means for classifying the quantized data into data having a representative value representing the quantized data and at least one set of classified data having a data value other than the representative value and for obtaining classification information data representing the classification;
• first coding means for coding the classification information data by using a first coding method;
• and
• second coding means for coding at least the classified data out of the data having the representative value and the classified data, according to a second coding method.

A computer-readable recording medium storing a program to cause a computer to execute a data compression method of obtaining compressed coded data by quantization of original data to obtain quantized data followed by coding and compression of the quantized data, the program comprising the procedures of:

• classification of the quantized data into data having a value representing the quantized data and at least one set of classified data representing a data value other than the representative value, and acquisition of classification information data regarding the classification;
• coding of the classification information data according to a first coding method;
• and
• coding of at least the classified data out of the classified data and the data having the representative value, according to a second coding method.