An efficient compression technique for ITU-T group 3 coded images using variable length codes with reduced average length

In this paper a set of variable Length codes are designed for source coding of data. The designed codes satisfy the properties of being uniquely decodable, prefix free codes and satisfy Kraft McMillan inequality. The designed prefix codes are used for compressing binary Image for Facsimile Transmission. The proposed Codewords have achieved reduced average length and increase in coding efficiency when applied to the set of standard CCITT images. The proposed codes have average length of 7.7 which is less compared to 8.63 of standard Modified Huffman codes used for CCITT Group3 compression. An improvement of up to 10.4% in coding efficiency and reduced average length of 1.24 bits/symbol is achieved for a particular CCITT image. The proposed scheme has less number of Codewords 71 compared to that of CCITT Group 3 standard codes which are 183 in number. The proposed Codewords requires less memory for encoding and decoding using lookup tables and as well as less CPU time for processing.