Browse Prior Art Database

ADAPTIVE PREDICTOR FOR HALFTONE OR LINE GRAPHICS

IP.com Disclosure Number: IPCOM000024717D
Original Publication Date: 1981-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 89K

Publishing Venue

Xerox Disclosure Journal

Abstract

A compressor consisted of a predictor and encoder is described in Figure 1. I - PREDICTOR ENCODER - L I I Figure 1 In a conventional document consisting of text and line graphics, a delta predictor using previous line data is quite efficient to remove the line by line redundancy and hence improve the overall data compression ratio. The delta predictor is described in U.S. Patent No. 3,524,926 by T. Starr of Xerox Corporation.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 58% of the total text.

Page 1 of 2

XEROX DISCLOSURE JOURNAL

Proposed Classification

Int. Cl. H04n 1/00

- PREDICTOR ENCODER -

ADAPTIVE PREDICTOR FOR HALFTONE OR LINE GRAPHICS U.S. Cl. 358/260 Henry H. Liao

A compressor consisted of a predictor and encoder is described in Figure 1.

I L I I

Figure 1

In a conventional document consisting of text and line graphics, a delta predictor using previous line data is quite efficient to remove the line by line redundancy and hence improve the overall data compression ratio. The delta predictor is described in U.S. Patent No. 3,524,926 by T. Starr of Xerox Corporation.

However, if the document is a halftoned or synthetic halftone pictures, the delta predictor becomes very inefficient. This is due to the non-existence of line by line correlation in pictures and the introduction of halftone 'pitch' frequency.

To solve this problem, an adaptive predictor consists of a vertical delta predictor and a horizontal delta-8 predictor is proposed. The adaptive predictor is best described by Figure 2.

 VERTICAL DELTA PREDICTOR

ENCODER

HORIZONTAL DELTA PREDICTOR Manual or

Automatic

Figure 2

Volume 6 Number 5 September/October 1981 28 1

[This page contains 1 picture or other non-text object]

Page 2 of 2

ADAPTIVE PREDICTOR FOR HALFTONE OR LINE GRAPHICS (Cont'd)

The selection of text/line graphic or halftone mode is done manually, or auto- matically if a halftone detector is implemented in the scanner.

The basic two modes of the adaptive predictor is described as follows:

1. For text or graphic inputs, a vertical...