Enhancement of coronary angiogram by estimation of local background

Coronary angiogram is an important examination tool in clinical medicine for the precise diagnosis of cardiac disease. It is obtained by injecting of the patient with a contrast medium through a catheter. This paper presents a method to increase vessel contrast and to attenuate background. The enhancement is achieved by subtracting the estimated background from a live (contrast-containing) angiogram. The multi-scale morphology opening, with structuring elements of different dimension for each pixel, is employed to get the estimation of background. The dimension of structuring element for each pixel is calculated by the response difference between opening filtering results of original image with different structuring elements. The proposed algorithm is tested on real x-ray angiogram.