Facsimile-images of the future

Summary form only given. Fax is immensely successful with over 100 million machines sold world-wide. It is successful because a fax machine is simple and easy to use as a stand-alone device, but it is also very versatile when combined with PC technology. This trend highlights the divergence between PCs and fax machines in image resolution. Many PC applications require resolutions as high as 600 dpi, for example desktop publishing, graphic design, while the highest resolution commonly supported by fax machines is 200 lines/inch. Clearly, transmission of the sort of images which can be generated by a PC places new demands on facsimile. There are at present three main standards for coding facsimile images that have been introduced within the last few years, of which the vast majority of machines use the simplest and oldest technique. This study compares the current standards with a fourth technique developed at De Montfort University called the contour tree format. This new format is a strict two dimensional representation of regions and offers some intrinsic advantages. A set of criteria was investigated with emphasis regarding the compression ratio using many different input conditions.