1. A method for acquiring biometric information, the method comprising: generating a plurality of frames representing image data for a finger, wherein each frame includes first and second directions, said first direction being generally perpendicular to a finger movement direction, said second direction being generally parallel to said finger movement direction; transferring a first of said plurality of frames to a reconstructed image buffer; for each of a remaining plurality of frames, determining new lines that have moved into each frame compared to lines in said reconstructed image buffer, wherein said determining comprises compensating for variations due to movement error by computing: a first correlation between a prior frame and a next frame, wherein rows from said prior frame have previously been added to said reconstructed image buffer, and wherein rows from said next frame will subsequently be added to said reconstructed image buffer; and a second correlation between said next frame and an extracted frame, wherein said extracted frame is extracted from most recently added rows to said reconstructed image buffer, and wherein at least one of said first and second correlations is derived from an averaged delay from two or more functions computed in said second direction; and updating said reconstructed image buffer by appending only said new lines from each of said remaining plurality of frames.