1. A method of reducing ring artifacts in tomographic images comprising the steps of: providing an original digitized projection measurement comprising a plurality of intensities corresponding to a domain of points on an 2-dimensional grid; operating on said original projection measurement with a filter wherein features of high radial frequency and low angular frequency are attenuated; forming a weighted mixture of said filtered projection measurement and said original projection measurement wherein ring artifacts in said original tomographic image are substantially reduced; reconstructing the projection measurement to form a tomographic image, and wherein operating on said original projection measurement comprises transforming said original projection measurement from a measurement space representation into a frequency space representation, filtering said frequency space representation, and transforming filtered frequency space representation back to the measurement space representation.