scholarly journals A new undersampling image reconstruction method based on total variation model

2012 ◽  
Vol 31 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Yang YANG ◽  
Zhe LIU ◽  
Meng ZHANG
2020 ◽  
Vol 28 (2) ◽  
pp. 155-172
Author(s):  
Yumeng Guo ◽  
Li Zeng ◽  
Jiaxi Wang ◽  
Zhaoqiang Shen

AbstractThe exterior cone-beam computed tomography (CBCT) appears when the x-rays can only pass through the exterior region of an object due to the restriction of the size of the detector, the energy of x-rays and many other factors. The exterior CBCT is an ill-posed inverse problem due to the missing projection data. The distribution of artifacts in exterior CBCT is highly related to the direction of missing projection data. In order to reduce artifacts and reconstruct high quality image, an image reconstruction method based on weighted directional total variation in cylindrical coordinates (cWDTV)is presented in this paper. The directional total variation is calculated according to the direction of missing projection data. The weights are set to reduce artifacts and preserve edges. The convexity of cWDTV and the relationship between cWDTV and classical TV are also illustrated to explain the advantages of our method. Simulated experiments show that our method can improve the performance on artifact reduction and edge preserving.


Author(s):  
Jingwen Wang ◽  
Xu Wang ◽  
Dan Yang ◽  
Kaiyang Wang

Background: Image reconstruction of magnetic induction tomography (MIT) is a typical ill-posed inverse problem, which means that the measurements are always far from enough. Thus, MIT image reconstruction results using conventional algorithms such as linear back projection and Landweber often suffer from limitations such as low resolution and blurred edges. Methods: In this paper, based on the recent finite rate of innovation (FRI) framework, a novel image reconstruction method with MIT system is presented. Results: This is achieved through modeling and sampling the MIT signals in FRI framework, resulting in a few new measurements, namely, fourier coefficients. Because each new measurement contains all the pixel position and conductivity information of the dense phase medium, the illposed inverse problem can be improved, by rebuilding the MIT measurement equation with the measurement voltage and the new measurements. Finally, a sparsity-based signal reconstruction algorithm is presented to reconstruct the original MIT image signal, by solving this new measurement equation. Conclusion: Experiments show that the proposed method has better indicators such as image error and correlation coefficient. Therefore, it is a kind of MIT image reconstruction method with high accuracy.


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