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Data Compression for Scanned Written Material

IP.com Disclosure Number: IPCOM000078579D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Muehldorf, EI: AUTHOR [+2]

Abstract

For scanned printed matter (numbers, letters, etc.) the binary electrical facsimile signals have long runs of 0's for the light background, and short strings of 1's and 0's representing the dark contrast print information. Such signals can be efficiently compacted by hardware shown in Fig. 1.

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Data Compression for Scanned Written Material

For scanned printed matter (numbers, letters, etc.) the binary electrical facsimile signals have long runs of 0's for the light background, and short strings of 1's and 0's representing the dark contrast print information. Such signals can be efficiently compacted by hardware shown in Fig. 1.

The 1's in the uncompacted facsimile (DATA IN) trip a 1-sensor and advance a first counter A. Upon reaching a predetermined value, the count in counter A is read into the header mapping unit via the header gate. The mapping unit selects a header most closely resembling the actual header and loads the header section H of the output register (if not the 0's in the register are the header).

As soon as counter A resets, it disables the header gate and enables counter
B. This allows the data stream to advance the count of counter B. The overflow of counter B or the next 1 in the data, enables the counter transfer gate to transfer the content of counter B to data section L of the output register. The header information in register section H and the count information in register section L, represent the compacted data for a code word. When this data is forwarded, counter B resets the compacting cycle is repeated.

The decompacter shown in Fig. 2 consists of a linear feedback shift register LFSR, connective gates (CONN) and a register-counter, which includes a header section for receiving the header portion of the compacted data.

The rece...