[Research about the gray-level correction in DSA].

How to eliminate the background of other tissue and to protrude the blood vessel information is the basic requirements in DSA. Because of the complexity and non-linearity of the X-ray imaging process, the common DSA technique cannot completely remove other tissue's image which lapped over the vessels. By experiments, this paper analyses and corrects the imaging process of the actual DSA system based on the "equivalent single energy" model, and the results indicate the validity of this method.

[The multi-resolution image registration algorithm for digital subtraction angiography].

The proposed registration algorithm based on wavelet transform is a multi-resolution block matching one, which exploits the hierarchical self-similarity of Digital Subtraction Angiography images. This method befittingly trades off between the estimation precision and computational complexity, because the registration precision is from coarse to fine, which reduces the searching complexity of motion vector. This technique has been proved that the convergence speed is exponential. The proposed method takes full advantage of the precise location both temporally and frequently which characterizes the wavelet transform. Both the matching speed and consistency are boosted without the loss of matching performance.