A comparative study of directional filters with application to angiogram image enhancement

In this paper, a comparative study of different directional filters in the context of angiogram image enhancement has been discussed. Generally, the angiogram images acquired by the X-ray modality suffer from non-uniform illumination and noise. These artifacts are directional in nature and can be suppressed with the help of directional analysis. To cater this problem, we have presented a comparison of directional filter banks (DFB), decimation-free directional filter banks (DDFB), and non-subsampled contourlet transform (NSCT). Experimental results demonstrate the effectiveness of NSCT and DDFB. In general, non-subsampled filter banks or decimation-free filter banks are suggested for image enhancement, especially for angiogram images.