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System and Method for Picture Image Processing Employing Transformation of Picture Data (Expired)

Author(s):
Quardt, Dennis; Reid-Green, Keith S.
Patent Issued:
Jul 18, 1995
Patent Number:
5,434,931
Source:
ETS Patent
Document Type:
Patent
Family ID:
24929022
Subject/Key Words:
Patent, Expired Patent, Image Processing, Pictures, Test Scoring, Document Scanning, Optical Scanning

Abstract

A method of picture image processing, and system for carrying out same, involves generation of a composite mapping function, for transforming gray scale values to different values in order to enhance contrast. A reduced range histogram is generated, involving removing a percentage of the total histogram counts from bottom and top sub-ranges and also removing spikes. The reduced histogram is then density averaged in order to obtain a first map function. A second map function is generated for interfacing with the characteristics of the printer to be used, and a composite mapping transform is generated by combining the two generated functions. After the composite mapping function is generated, each gray value of the image data set is transformed in accordance with the composite function, for use in printing, thereby providing an enhanced contrast image.

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