title: A robust generalized fuzzy operator approach to film contrast correction in digital subtraction radiography.
abstract: Digital subtraction radiography requires close matching of the contrast in each pair of X-ray images to be subtracted. Previous studies have shown that nonparametric contrast/brightness correction methods using the cumulative density function (CDF) and its improvements, which are based on gray-level transformation associated with the pixel histogram, perform well in uniform contrast/brightness difference conditions. However, for radiographs with nonuniform contrast/ brightness, the CDF produces unsatisfactory results. In this paper, we propose a new approach in contrast correction based on the generalized fuzzy operator with least square method. The result shows that 50% of the contrast/brightness errors can be corrected using this approach when the contrast/brightness difference between a radiographic pair is 10 U. A comparison of our approach with that of CDF is presented, and this modified GFO method produces better contrast normalization results than the CDF approach.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China. ccleung@eee.hku.hk
authors.forename: Chung-Chu
authors.initials: CC
authors.lastname: Leung
mesh_terms: D017143:Fuzzy Logic; D006801:Humans; D008954:Models, Biological; D011856:Radiographic Image Enhancement; D011857:Radiographic Image Interpretation, Computer-Assisted; D019252:Radiography, Dental, Digital / Q000379:methods*