Electrical impedance tomography (ET) is a technique for reconstructing conductivity of an inhomogeneous medium by injecting current at the boundary of an object and measuring the resulting voltage changes. ET techniques have been widely adopted for visualizing distributions of materials in industrial processes. In comparison to other tomography modalities, ET's advantages include low cost, rapid response, no radiation and being non-intrusive. In this paper, a group of most widely adopted electrical imaging algorithms are compared based on imaging time, correlation coefficient, the relative error, the objective function value, iterative times and convergence speed in a visualization tool OPTICS. Experiment results show the applicable ranges, limitations and complementary natures of different imaging algorithms.