1. A method for reconstructing image data corresponding to a desired two-dimensional image from initial tomographic data associated with a plurality of initial tomographic projections of said desired image, comprising: backprojecting said initial tomographic data to form backprojected image data; selecting a vector family to decompose said backprojected image data from the group consisting of 1-D orthogonal wavelet packet basis, 2-D orthogonal wavelet packet basis, 1-D biorthogonal wavelet packet basis, 2-D biorthogonal wavelet packet basis, 1 -D wavelet packet frame, 2-D wavelet packet frame, 1-D complex wavelet frame, 2-D complex wavelet frame, 1-D complex wavelet packet frame, and 2-D complex wavelet packet frame; decomposing said backprojected image data to generate decomposed coefficients associated with said selected vector family; diagonally operating on said decomposed coefficients to generate modified decomposed coefficients; and recomposing said image data corresponding to said desired two- dimensional image from said modified decomposed coefficients.