Istvan Sebestyen

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.

Public text and data services in the FRG

Abstract This paper provides some observations on the development of public text and data services in the Federal Republic of Germany. Statistics from the PTT in the FRG are used to discuss particular services such as telex, teletex, videotex, facsimile and the transmission of digital data. A brief outline of future developments towards the introduction of an ISDN in the FRG, is given.

A practical advice to international informatics access: use what you have] Why not Telex?

Abstract This article sums up the authors experiences with international informatic access projects. As a rule, for such projects only limited amount of resources are available and often many technical compromises have to be made. In the field of international informatics access projects, it is not only the latest technology that matters. Often with simple, well-known methods, such as the Telex, remarkable results can be achieved. In many less developed countries this is still the only available international infrastructure for data communication.