High Speed Reprojection And Its Applications
Carl R. Crawford, James G. Colsher, Norbert J. Pelc, Albert H. R. Lonn · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1988
Reprojection is the process by which projections are produced from an image such that, if these projections are filtered and backprojected, they yield the original image. Because of the computational expense of reprojection, algorithms that employ this process have never been widely used. A method is presented that enables an unmodified backprojector to be used as a reprojector. Because backprojectors are designed to exploit the parallelism in the backprojection algorithm, the time required to obtain reprojections is significantly reduced. Another method, based on the Fourier Slice Theorem, is presented that enables a general purpose array processor to be used as a high speed reprojector. It is also shown that the parameters of the reprojection algorithm can be adjusted to decrease significantly the time required to perform an application that uses reprojection. Finally, two applications of reprojection in computed tomography are discussed.