A gradient-directed unsharp masking algorithm for synchrotron radiation angiography

An algorithm for digital processing of synchrotron radiation digital subtraction intravenous angiographies (intravenous SYRDA) is presented. It is used to enhance the coronary arteries hidden behind the heart chambers and the aorta (which are normally filled with contrast medium and thus are opaque). In order to remove these large structures, a gradient operator computed over a very large area is used. The edges of the large structures are suppressed by evaluating the gradient in each pixel of the image. Some preliminary results with a synthetic image and an image taken from a human subject are presented. The performance is found to be good in terms of both image quality and computational speed