Computer Simulation of Gray Scale Coding Techniques.
Abstract
It is desirable in many cases to transmit gray scale imagery over a facsimile system such as Group 3 or 4, as defined by the CCITT. At the present time, there is no standard provision for providing this function. Dither coding is a new technique which permits this to be accomplished with very little modification to a conventional facsimile system. The only change required is related to the threshold of the device which converts the input analog signal to a digital signal. Normally, the threshold is fixed at the nominal midpoint between peak black and peak white. In dither coding, this threshold is continually dithered or jittered, to different amplitude values from sample to sample in a pseudo-random fashion. The purpose of Task 2.0 is to compare the compression and output image quality of dither coding techniques with the NATO standard STANAG 5000 coding technique. Originator-supplied keywords include: Facsimile; Gray scale; Dither; STANAG 5000; Compression; Random dither; and Clumped dither.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 13, 1984
- Accession Number
- ADA152414
Entities
Organizations
- Delta Information Systems (United States)