Browse Prior Art Database

Reduction of Data Representing One Pel Line

IP.com Disclosure Number: IPCOM000039872D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR

Abstract

This article describes a method for reducing the number of bits for representing gray levels of pels (picture elements) in one scan line of a document by comparing the gray level of the succeeding pels to find out turning points, determining variations between (a) a virtual line connecting two pels at the turning points and (b) the gray levels of intermediate pels existing between the two pels at the turning points, and forming a data stream for each virtual line which includes the gray levels of the two pels, the number of the intermediate pels and the variations of the intermediate pels. Referring to Fig. 1, a horizontal axis represents pels of a document and a vertical axis represents gray levels which changes between level 0 and level 255. Exemplary gray levels Y0 through Y10 of pels X0 through X10 are shown.

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Reduction of Data Representing One Pel Line

This article describes a method for reducing the number of bits for representing gray levels of pels (picture elements) in one scan line of a document by comparing the gray level of the succeeding pels to find out turning points, determining variations between (a) a virtual line connecting two pels at the turning points and (b) the gray levels of intermediate pels existing between the two pels at the turning points, and forming a data stream for each virtual line which includes the gray levels of the two pels, the number of the intermediate pels and the variations of the intermediate pels. Referring to Fig. 1, a horizontal axis represents pels of a document and a vertical axis represents gray levels which changes between level 0 and level 255. Exemplary gray levels Y0 through Y10 of pels X0 through X10 are shown. In the first step, the gray levels of the pels X0 through X1679 are compared with each other to find the pels Y3, Y5, Y7 and Y10 at the turning points. The turning points are selected so that the variations
Y1, Y2, Y4, Y6, Y8 and Y9 of the intermediate pels Y1, Y2, Y4, Y6, Y8 and Y9 are smaller than a predetermined range, such as value
16. The variation, such as Y2, represents the difference between an actual gray level of the pel Y2 and a virtual line L1 which connects the pels Y0 and Y3 .

(Image Omitted)

In the second step, the data stream shown in Fig. 2 (A), which represents the gray levels of the pels on o...