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Decompressing Run-Length Compressed Data for Use in Matrix Printers With Sweeps Comprising Several Dot Lines

IP.com Disclosure Number: IPCOM000046065D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Bechtle, B: AUTHOR [+2]

Abstract

For compressing data transmitted bit-serially line-by-line, so-called run-length methods have proved satisfactory. In accordance therewith, a bit sequence 0000000111100000

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Decompressing Run-Length Compressed Data for Use in Matrix Printers With Sweeps Comprising Several Dot Lines

For compressing data transmitted bit-serially line-by-line, so-called run- length methods have proved satisfactory. In accordance therewith, a bit sequence 0000000111100000

can be compressed to 7(w) 4(b) 5(w)

(w = 0 = white; b = 1 = black).

A simple approach for generating decompressed data from the run- length information of subjacent lines (Fig. 1)

comprises the following steps:

1. The bit information of the first position (Fig. 2)

of all subjacent lines is derived from the length data

L1 of the first column in Fig. 1.

2. The length data L1 of the first column in Fig. 1

are decremented by "1" until a "0" occurs in one

position. Based on the values of Fig. 1, Fig. 3 is

obtained after "l" has been subtracted 3 //times.

3. The "3_" indicates that the bit column in Fig. 2

appears three times in succession (Fig. 4).

4. The "0" in Fig. 3 is replaced (Fig. 5) by the

value L2 following L1 in Fig. 1.

5. For this information, the initial bit column would

be (Fig. 6).

6. Subsequently, "1" is subtracted several, in this

case, 4/_/ times from the values in Fig. 5 until a "0"

value (Fig. 7) is obtained.

7. The "4/_/" in step 6 shows that the bit column in

Fig. 6 reoccurs altogether four times, so that the

following bit pattern (Fig. 8) is obtained.

8. The "0" value in Fig. 7 is replaced by value L2

(in this case, 4(b)) following L1, and decrementation

by "1", etc., is...