公开(公告)号：FR2831351A1

公开(公告)日：2003-04-25

申请号：FR0113519

申请日：2001-10-19

Applicant: ST MICROELECTRONICS SA

Inventor： TISSE CHRISTEL LOIC

IPC: G06K9/00 ,  G06K9/52 ,  H03H17/02 ,  H03H17/00 ,  G02B5/20 ,  G06K9/46

Abstract: The bandpass filter has a passband which is real, bi-dimensional, oriented along the phase axis and resulting from the product of pair of identical one-dimensional Hamming windows. The transfer function of each window is given as Xi(f)= alpha i+(1- alpha i)\*cos( pi \*(f-fqi)\/f0i), where f is the current frequency, alpha i is a real number between 0 and 1, fqi is central frequency of the passband and f0i is half of the passband centered on fqi.

公开(公告)号：FR2838849A1

公开(公告)日：2003-10-24

申请号：FR0204804

申请日：2002-04-17

Applicant: ST MICROELECTRONICS SA

Inventor： TISSE CHRISTEL LOIC

IPC: G06K9/00 ,  G06K9/52

Abstract: To identify the direction of the furrows within an image, each pixel is checked to calculate a value taking account of the neighboring pixels in all directions. This takes account of an even number of pixels in each direction, in a scanning process. The procedure provides identification of the orientation of the furrows in a digital or analogue image representing a fingerprint. For each pixel the process includes calculating a value taking account of the neighboring pixels in all directions, and scanning the image line by line in a bidirectional process. The orientation calculation takes into account an even number (L-1)/2 of pixels on either side of the current pixel, in a number of predetermined directions. It does not include calculation of the orientation for pixels around the perimeter of the image for (L-1)/2 pixels in height or in width. The process uses a bidirectional shift register circuit (Rj) authorizing loading words (Bij) into each register in parallel.

公开(公告)号：FR2831302A1

公开(公告)日：2003-04-25

申请号：FR0113522

申请日：2001-10-19

Applicant: ST MICROELECTRONICS SA

Inventor： TISSE CHRISTEL LOIC ,  BARBEYRAC DAMIEN

IPC: G06T7/00 ,  G06K9/00 ,  G06K9/48 ,  G06K9/52 ,  H04N1/41 ,  H04N7/30 ,  G06K9/46 ,  A61B3/14 ,  G06F17/14 ,  G06K9/64

Abstract: Method for frequency, modulation and phase coding of a digital representation of an annular element has the following steps: application (301) of a polar conversion with a constant angle for folding the element into a rectangular shape; transfer into the frequency domain unit a Fourier transform; band-pass filtering of the resultant data; application of a Hilbert transform; application of an inverse Fourier transform; and extraction of phase and modulation data in the spatial domain.