针对数字减影图象中，因运动引起的图象质量下降问题，提出了一种基于图象配准的数字减影图象增强算法，该算法通过选择合适的控制点和相似测度，采用快速样条插值算法以及鲍威尔优化搜索方法，并用块匹配方法对造影图象和掩膜图象进行配准，实验结果表明，配准后的减影图象质量良好，不仅具有较高的临床诊断价值，并且该算法具有较快的计算速度。

A serious disadvantage of Digital subtraction angiography(DSA), inherent to the subtraction operation, is its sensitivity to patient motion. The resulting artifacts frequently reduce the diagnostic value of the images. This paper presents an algorithm based on registration for the image enhancement of DSA, it employs block matching method for the registration of mask image and live image. Because of the high computational cost, it is usually not admissible to determine the displacement explicitly for every pixel. This has led to the concept of control-point based registration. Most control-point based registration algorithms published so far employ regular grids. However, control point selection should be image-feature based. Our experiments have demonstrated the advantage of algorithm with edge based control point selection over algorithms based on regular grids. Other aspects in our algorithm include similarity measure, interpolation and search strategy: energy of the histogram of difference is selected as the similarity measure, fast spline interpolation is used in order to implement the algorithm fast and get better result, and Powell optimization strategy is used as the search strategy by carefully choosing block size. The experiments demonstrate that the subtraction images after registration are of high quality and much more diagnostic value, the algorithm is also fast to be implemented.