Browse Prior Art Database

Black and White Representation of a Grey Scale Picture

IP.com Disclosure Number: IPCOM000077932D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Morrin, TH: AUTHOR

Abstract

A method has been provided for arranging black and white picture elements in a sketch-like manner, to represent grey scale images. Essentially, the method includes the following steps: 1) establishing ambient grey level by computing the average of sample points in the neighborhood of the "current" sample (including the previous scan line), 2) taking the differences in adjacent grey values for edge detection (in both horizontal and vertical directions), 3) linearly combining the ambient grey level, composite difference values, and current grey level into a discriminant for making a black or white decision, and 4) making a black or white decision output.

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Black and White Representation of a Grey Scale Picture

A method has been provided for arranging black and white picture elements in a sketch-like manner, to represent grey scale images.

Essentially, the method includes the following steps:
1) establishing ambient grey level by computing the average of

sample points in the neighborhood of the "current" sample

(including the previous scan line),
2) taking the differences in adjacent grey values for edge

detection (in both horizontal and vertical directions),
3) linearly combining the ambient grey level, composite

difference values, and current grey level into a discriminant

for making a black or white decision, and
4) making a black or white decision output.

The method for making a black-white decision on each scanned picture element of a grey scale image, is shown in the form of a functional block diagram as Fig. 1. The current grey value is represented by y, and the local differencing operator (of adjacent grey values) is represented in exemplary value by x. The ambient averaging operator (ambient grey level) is represented in exemplary value by b.

With this arrangement, x is subtracted from y at a weighted summer, and the output, y-mx is fed to a comparator, which compares the value of y-mx with b, the input from the local averaging operator.

If the value of (y-mx) is greater than b, then the decision for a black or white picture element is black. On the other hand, if the value of (y-mx) is less than b, then th...