A method is provided for averaging a sequence of image frames. A noise-reducing filter is applied to the image frames to generate filtered frames. A deconvolution filter is applied to the filtered frames to generate corresponding deconvolved frames. The filtered frames are transformed by an affine transformation to align them, generating aligned frames. The aligned frames are motion corrected by non-linear transformation based on intensity rank matching, generating a sequence of motion-corrected frames. The motion-corrected frames are averaged to generate a resultant frame.