Fumitaka Ono

Bi-level image coding with MELCODE-comparison of block type code and arithmetic type code

It is shown how to encode and transmit binary Markov sources using a set of block codes called MELCODE. Fill symbol control is used to manage the transmission order of codewords with limitation of memory size. MELCODE is extended to arithmetic-type code, and the calculation accuracy of coding address is clarified. Block codes and arithmetic codes are compared in terms of memory size and coding efficiency through the simulation of bilevel image coding, showing an improvement in coding efficiency.<<ETX>>

Technical features of the JBIG standard for progressive bi-level image compression

Abstract The JBIG coding standard like the G3 and G4 facsimile standards defines a method for the lossless (bit-preserving) compression of bi-level (two-tone or black/white) images. One advantage it has over G3/G4 is superior compression, especially on bi-level images rendering greyscale via halftoning. On such images compression improvements as large as a factor of ten are common. A second advantage of the JBIG standard is that it can be parameterized for progressive coding. Progressive coding has application in image databases that must serve displays of differing resolution, image databases delivering images to CRT displays over medium rate (say, 9.6 to 64 kbit/s) channels, and image transmission services using packet networks having packet priority classes. It is also possible to parameterize for sequential coding in applications not benefiting from progressive buildup. It is possible to effectively use the JBIG coding standard for coding greyscale and color images as well as bi-level images. The simple strategy of treating bit-planes as independent bi-level images for JBIG coding yields compressions at least comparable to and sometimes better than the JPEG standard in its lossless mode. The excellent compression and great flexibility of JBIG coding make it attractive in a wide variety of environments.