An Improved Algorithm Based on Landweber-Tikhonov Alternating Iteration for ECT Image Reconstruction

Abstract

Aiming at the problem of "soft field" and ill state existing in image reconstruction proceeding of electrical capacitance tomography (ECT) system. An improved image reconstruction algorithm is proposed in this paper. For which, the pseudo-inverse matrix instead of transport matrix of sensitivity is directly used as the initial image value, and an alternate iteration procedure based on Landweber-Tikhonov algorithm is adopted to perform direct image reconstruction. Firstly, the Landweber algorithm is used to improve the initial value, and then the results are used as the inputs of Tikhonov regularization algorithm. The procedure is repeated alternately to search an ideal reconstructed image. This strategy can effectively solve the problem caused by the "soft field" and ill-state problems which always grows out poor quality of the reconstructed image. To test the availability and the effectiveness of the proposed algorithm, it is used to the image reconstruction of ECT system. The correlation coefficient and relative error are used as evaluation criteria for image quality, and the representative algorithms (e.g., LBP, Tikhonov, and Landweber ) are selected for comparison. Simulation experiments show that our algorithm is with well performance both in terms of subjective imaging effect and objective criteria under the same iteration steps with the compared algorithms. Moreover, the convergence speed of the proposed algorithm outperforms the compared algorithms.