Patent ID: 7194116

Claim:
A method for acquiring biometric information, the method comprising: generating a plurality of frames representing image data for a finger, wherein each frame is associated with a matrix, the matrix having first and second dimensions, wherein the first dimension corresponds to a first direction, and the second dimension corresponds to a second direction; transferring a first of said plurality of frames to a reconstructed image buffer; for each of the 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 correlation between a prior frame and a next frame and a correlation between the prior frame and an extracted frame, wherein at least one correlation is derived from an averaged delay from two or more functions computed in the second direction, and wherein said determining further comprises: extracting a portion of the image data from said reconstructed image buffer and placing said extracted image data portion into a frame buffer F k ; decimating the extracted image data portion in said frame buffer to obtain a decimated data array F k d ; extracting a second portion of said image data portion from said reconstructed image buffer into a frame buffer {circumflex over (F)} k ; decimating said frame buffer to obtain a decimated data array {circumflex over (F)} k d ; decimating a current one of said plurality of frames F k+1 d ; calculating a first and second correlation coefficient matrices in accordance with the following equations: C k,k+1 =P k F k d ( F k+1 d ) T P k+1 and Ĉ k,k+1 ={circumflex over (P)} k {circumflex over (F)} k d ( F k+1 d ) T P k+1 where T denotes a transpose matrix and P ∈ R M×M is a diagonal matrix with the i th element being defined by: 1 ∑ ( F d ⁡ ( i , j ) ) 2 and {circumflex over (F)} k d and F k+1 d represent two matrices that are the correlation functions of the decimated matrices of the prior frame F k and the extracted frame {circumflex over (F)} k ; determining an average of the τ th diagonal of said correlation coefficient matrices C k,k+1 and Ĉ k,k+1 ; determining peak correlation locations; and calculating the number of new lines that have moved into the current frame; and updating said reconstructed image buffer by appending only the new lines from each of said remaining plurality of frames.