Experiments with a New Message Format for Digital Representation of Photographs.
Research and development technical rept.,
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
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Ordinarily, a black-and-white photograph is digitally encoded in the PCM format the picture is dissected into L square samples and the brightness of each sample is represented by a binary number of k bits. Consequently, the picture message contains kL square bits, including L square most-significant and exactly L square of each subsequent significance rank. With the aid of a digital computer and special picturemagnetic-tape inter-conversion equipment, experiments were performed to evaluate a radically different structure for the picture message. In effect, a kL square-bits message in the experimental format includes more than L square bits of some, more important, significance ranks and less than L square of other, less important, ranks. The number of brightness levels remains 2 to the k power. Pictures decoded from the experimental format were compared with pictures reconstructed from PCM-format messages having the same or larger number of bits. They seem to indicate that a well-chosen embodiment of the experimental format offers better quality than PCM under the constraints of fixed message length and fixed number of brightness levels. Photographic copies of compared pictures are included in the report. Author
- Computer Hardware
- Recording and Playback Devices
- Non-Radio Communications