Browse Prior Art Database

Pseudo Halftone Generation

IP.com Disclosure Number: IPCOM000089004D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brandley, CR: AUTHOR

Abstract

In the printing of pseudo-halftone data, the print matrix may beat with the halftone frequency and generate Moire patterns as the result.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Pseudo Halftone Generation

In the printing of pseudo-halftone data, the print matrix may beat with the halftone frequency and generate Moire patterns as the result.

A solution is to average each scan element spot (PEL) with its neighborhood to prevent the Moire pattern.

Thus, with the following data (S) array, the averaging to establish the print data (A) array may be accomplished in accordance with the following algorithm.

Input Array S(1) S(2) S(3) S(4) S(5) S(6) S(7) S(8) S(9) S(10)

S(11) S(12) S(13) S(14) S(15)

Algorithm A(7) = (S(1) S(2) S(3) S(6) S(8) S(11) S(12) S(13))/8

A(8) = (S(2) S(3) S(4) S(7) S(9) S(12) S(13)

S(14))/8

A(9) = (S(3) S(4) S(5) S(8) S(10) S(13) S(14)

S(15))/8

Print Array A(1) A(2) A(3) A(4) A(5) A(6) A(7) A(8) A(9) A(10)

A(11) A(12) A(13) A(14) A(15).

The averaging should only be applied to halftone or gray scale areas and not to line copy. Criteria should be used to differentiate line copy, such as sampling a delta (of a combination of 'ELs) across the input array. Line copy data should be thresholded without averaging.

1