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Efficient Processing of Scanner Data for Matrix Printing

IP.com Disclosure Number: IPCOM000046651D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Hehl, H: AUTHOR

Abstract

In order to change the grey value association, scanner data of different grey values of an image scanned dot-by-dot are processed before being fed to a matrix printer. For this purpose, the image to be printed may be reproduced in its original size or in an enlarged form. GREY VALUE ASSOCIATION By means of a program, the grey values of the scanner data are associated with other grey values. Print points or no print points are assigned to the scanner points of particular grey values. The height of a grey value, for example, 5, decides whether a print point is printed or not. For a 3 x 3 grey value matrix of only fives, for example (Fig. 1), a repeatable threshold matrix (Fig. 2) is used. The values of this matrix are compared with those of the grey value matrix.

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Efficient Processing of Scanner Data for Matrix Printing

In order to change the grey value association, scanner data of different grey values of an image scanned dot-by-dot are processed before being fed to a matrix printer. For this purpose, the image to be printed may be reproduced in its original size or in an enlarged form. GREY VALUE ASSOCIATION By means of a program, the grey values of the scanner data are associated with other grey values. Print points or no print points are assigned to the scanner points of particular grey values. The height of a grey value, for example, 5, decides whether a print point is printed or not. For a 3 x 3 grey value matrix of only fives, for example (Fig. 1), a repeatable threshold matrix (Fig. 2) is used. The values of this matrix are compared with those of the grey value matrix. If they are higher or lower, this is indicated by a binary 1 or a binary 0, respectively. As a result, a matrix (Fig. 3) with binary values is obtained which is used to control the matrix printer. The threshold matrix is, for example, structured in such a manner that a degree of blackening increasing from the inside towards the outside is obtained. If the grey values of the scanner points are to be associated with other grey values, this is done by changing the numerical values in the threshold matrix. A. REPRODUCING THE IMAGE IN ITS ORIGINAL SIZE The scanner data are supplied in a serial position sequence (Fig. 4). The numbers indicated in this figure denote the positions, under which particular grey values are stored. It is assumed that the scanner data are to be reproduced by the matrix printer on one page in the order shown in Fig. 5. It is also assumed that the printer permits handling a 5-bit high stripe in a single sweep. The binary print data are assumed to be fed to the printer in 4-bit wide and 5-bit high blocks (Fig. 6). Generally, several bit blocks are handled in a sweep. The bit block shown in Fig. 6 is only an example which, similar to Fig. 3, provides the results of a comparison of a threshold matrix with the grey values of a matrix with scanner data. A position mask (Fig. 7) denotes the positions in the scanner data flow (Fig. 4), whose grey values are to be compared with those of the threshold matrix (Fig. 8). It is assumed that the position mask (Fig. 7) and the threshold matrix (Fig. 8) continuously cover the entire print page (Fig. 5) in matrix form (Fig. 9). As the position mask has one line more than the threshold matrix, the following values to be compared (Fig. 10) are obtained for the hatched position field designated as 11 in Fig. 9. (The first number denotes the position at which the scanner data grey values to be compared are stored and the second number the relevant value of the threshold matrix.) For this purpose, the last line of the position mask is also compared with the first line of the threshold matrix....