Huffman encoder, Huffman encoding method and recording medium having program for Huffman encoding process recorded thereon

摘要

A Huffman encoder and a method for Huffman encoding in which a data compression rate can be easily changed and a recording medium having a program for a Huffman encoding process recorded thereon. A quantizer quantizes DCT coefficients output by a DCT device to output quantized DCT coefficients. A comparator judges a quantized DCT coefficient to be an invalid coefficient when the absolute value of the DCT coefficient is equal to or smaller than a threshold and judges the quantized DCT coefficient to be a valid coefficient when the absolute value of the DCT coefficient is greater than the threshold. A run length counter counts the number of consecutive invalid coefficients to output run lengths and outputs valid coefficients. An encoder performs encoding based on the valid coefficients and the run lengths to output encoded data.