An imaging system includes a two-dimensional detector having a plurality of cells wherein each cell is configured to detect energy or signal passing through an object. The imaging system includes a computer programmed to acquire imaging data for the plurality of cells, identify a cell to be corrected, based on the imaging data, interpolate Ix and Iy for the identified cell based on neighbor cells, and calculate local gradients gx and gy between the identified cell and its neighbor cells based on the interpolation. The computer is further programmed to calculate weighting factors wx and wy based on the local gradients, calculate a corrected final value I(0,0) for the identified cell, and correct the identified cell with the corrected final value.