A conebeam computed tomography scanner (10) acquires conebeam projection data along a generally helical source trajectory around an examination region (14). An exact reconstruction processor (40) includes a convolution processor (42) and an aperture weighted backprojection processor (46, 66). The convolution processor (42) performs at least one convolution of the acquired projection data. The convolving operates on projection data falling within an exact reconstruction window (38) and on at least some redundant projection data falling outside the exact reconstruction window (38) to produce convolved projection data. The aperture-weighted backprojection processor (46, 66) performs aperture-weighted backprojecting of the convolved projection data using an aperture weighting function that weightedly combines at least some convolved redundant projection data with convolved projection data falling within the exact reconstruction window (38) to generate a reconstructed image with contributions from redundant projection data.