A new method of efficient measurement for sub-pixel image motion of space camera

In order to measure the sub-pixel image motion of space camera which is caused by satellite attitude's instability or vibration, a method for image motion detection based on combination of corner detection and improved phase correlation is proposed in this paper. Firstly, it extracts feature points from the serial images using Harris detector. Then, the corners are used to construct a binary matrix. After that, the phase correlation for the constructed image is processed to get the relative output by taking the advantage of Fourier transform symmetry. Simultaneously, Blackman window function is taken to inhibit spectrum leakage caused by truncation for the output image. Finally, the sub-motion vector is calculated with centroid of mass calculation. On the basis of the theory proposed for measuring image motion, experiments for different sub-images with different image motions are carried out. Compared with other motion vector detection technology by soft algorithm, the simulations results show that this method not only inhibits the boundary effect but also avoids bringing truncation error, which improves the accuracy of estimation of image motion. Besides, this method effectively reduces the cost of computation and storage, improving the output SNR with good unimodality and real time property. The measure accuracy is good when the sub-image size is larger than 128128. The accuracy does not change with different scene of input images. The RMS error of image motion measurement can be controlled below 0.1 pixels, which meets the requirement of the space camera. Copyright © 2015 Binary Information Press.