Image preprocessing for 3-D reconstruction from biplane angiograms

The accuracies of systems for Quantitative Coronary Angiography, as well as for 3-D reconstruction from biplane angiograms, strongly depend on the quality of the used image data. To complete their highly accurate reconstruction system, the authors developed several methods for equalizing gray value contrasts to enhance vessel detection, and improved algorithms for elimination of geometric image distortions. Conventional rectification algorithms using a regular grid mostly neglect dynamic influences like the magnetic field of the Earth. To avoid the necessity of determining the distortion for each possible angulation individually, the authors interpolate a specific rectification polynomial from two extrema.