Browse Prior Art Database

Graphic Communication System Incorporating Scan Resolution Control

IP.com Disclosure Number: IPCOM000078423D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Cassada, T: AUTHOR [+2]

Abstract

A graphic communication system incorporates a scan resolution controller for automatically reducing the scan resolution, whenever the data signals generated by a high-resolution scan cannot readily be compressed in the buffer storage available.

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Graphic Communication System Incorporating Scan Resolution Control

A graphic communication system incorporates a scan resolution controller for automatically reducing the scan resolution, whenever the data signals generated by a high-resolution scan cannot readily be compressed in the buffer storage available.

Scanner 11 optically scans documents with a high-resolution scan and provides an output bit stream through AND gate 13 to compression coder 15, which in turn provides a compressed output bit stream to buffer storage 17. The information transmitted to buffer storage 17 is transmitted over channel 19 at a lower bit rate than the information supplied by scanner 11. Compression ratio monitor 21 provides an output signal whenever the compression ratio drops below a preset minimum. If the compression ratio remains below the preset minimum for a preset number of scan lines, compression ratio monitor 21 provides an output signal to mode control 23, which in turn causes scanner 11 to thereafter scan the remaining Portion of a document at a low resolution. The output of the scanner is provided through AND gate 25 directly to buffer 17 without compression coding. Should a buffer overflow condition nevertheless exist, overflow monitor 27 provides a reset signal to scanner 11 and a second signal to mode control 23, thereby causing the entire document to be rescanned at a low-resolution. Buffer 17 is sized to adequately accommodate the output of scanner 11 in the low-res...