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Investigation of basic imaging properties in digital radiography. 4. Effect of unsharp masking on the detectability of simple patterns
Author(s) -
Loo LehNien D.,
Doi Kunio,
Metz Charles E.
Publication year - 1985
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.595775
Subject(s) - unsharp masking , weighting , masking (illustration) , observer (physics) , computer science , optical transfer function , contrast (vision) , artificial intelligence , image quality , computer vision , image processing , mathematics , optics , physics , image (mathematics) , acoustics , art , visual arts , quantum mechanics
The signal‐to‐noise ratios (SNRs) of simple radiologic patterns processed by the unsharp‐masking technique were calculated on the basis of a statistical decision theory model that includes both the observer's visual transfer function and a noise component internal to his eye–brain system. For a variety of processing parameters, the contrast‐detail diagrams predicted from this SNR agreed qualitatively with experimental results obtained in observer performance studies. Unsharp masking with a large mask and a large weighting factor improved the detection of square objects to a level comparable with that achieved by the overall contrast enhancement technique using a factor of 4. However, unsharp masking with a small mask and a large weighting factor can substantially degrade the detectability of these objects. The potential practical utility of the unsharp‐masking technique is discussed.