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A robust digital method for film contrast correction in subtraction radiography
Author(s) -
Ruttimann Urs E.,
Webber Richard L.,
Schmidt Edgar
Publication year - 1986
Publication title -
journal of periodontal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.31
H-Index - 83
eISSN - 1600-0765
pISSN - 0022-3484
DOI - 10.1111/j.1600-0765.1986.tb01484.x
Subject(s) - subtraction , radiography , contrast (vision) , histogram , digital radiography , nonparametric statistics , monotonic function , artificial intelligence , parametric statistics , mathematics , matching (statistics) , computer science , computer vision , medicine , radiology , image (mathematics) , statistics , mathematical analysis , arithmetic
Digital subtraction radiography requires close matching of the contrast in the films to be subtracted. A digital method is presented permitting the retrospective correction of film contrast differences. The method is nonparametric and derives the required gray level transformation directly from the histograms associated with the radiographs. This transform is shown to be unique and monotonic. It is based on fewer theoretical assumptions than a previously described parametric correction method, and it performs significantly better in reducing the contrast mismatch measured by the standard deviation of the gray levels in the subtraction image.