In a diagnostic imaging system (10) two-dimensional projection data is collected in a data memory (30). The data is sorted into the data sets collected during selected cardiac phases. A re-binning processor (38) re-bins the projection data into a parallel ray format. An adaptive filter (70) filters the parallel ray format data with each of a plurality of different filter channels based on a calculated photonic noise of each reading and assuming an arbitrary noise reduction factor, different for each filter channel. A convolver (78) convolves the data filtered with each of the filter channels. A noise reduction factor processor (84) determines the actual noise reduction factor occurring due to the weighted averaging of readings contributing to each voxel .nu. at an angle .theta..epsilon.[0, 7.pi.). A weighting processor (90) weights the convolved data from each of the filter channels based on the channels' noise reduction factors and the actual noise reduction factor. A backprojector (98) backprojects the combined weighted sum of projections to build an image representation that can be displayed in a human readable format.