Device for acquiring images of patterns formed by furrows in the skin of fingers or the palm of the hand
View Patent ↗A device for acquiring images of a print of at least a portion of a user's hand, the device comprising a stand defining an acquisition zone extending substantially in a plane, an optical acquisition member that is fastened to the stand to have a field of view covering the acquisition zone, and a processor unit connected to the acquisition member to process an image signal coming therefrom, wherein: the stand is arranged to provide an empty space zone containing the acquisition zone and forming a passage for said portion of the hand while moving parallel to the plane; the device includes at least one projector member for projecting a light test pattern of at least two colors into the acquisition zone; the optical acquisition member has a depth of field extending on either side of the acquisition zone and it possesses a color sensor having an acquisition speed that is sufficient to capture at least one color image of said portion of the hand moving at a predetermined maximum speed of movement; and the processor unit is arranged to extract from the color image signal a monochrome image in each of the projected colors, to reconstitute a texture of said portion of the hand from at least one of the monochrome images, and to reconstitute a shape from at least one of the monochromic images.
1. A device for acquiring images of a print of at least a portion of a user's hand, the device comprising a stand defining an acquisition zone extending substantially in a plane, an optical acquisition member that is fastened to the stand to have a field of view covering the acquisition zone, and a processor unit connected to the acquisition member to process an image signal coming therefrom, wherein:
the stand is arranged to provide an empty space zone containing the acquisition zone and forming a passage for said portion of the hand while it is moving parallel to the plane;
the device includes at least one projector member for projecting a light test pattern of at least two colors into the acquisition zone;
the optical acquisition member has a depth of field extending on either side of the acquisition zone and it possesses a color sensor having an acquisition speed that is sufficient to capture at least one color image of said portion of the hand moving at a predetermined maximum speed of movement; and
the processor unit is arranged to extract from the color image signal a monochrome image in each of the projected colors, to reconstitute a texture of said portion of the hand from at least one of the monochrome images, and to reconstitute a shape from at least one of the monochromic images.
2. A device according to claim 1 , in which the field of the optical acquisition member is of a width sufficient for the acquisition zone to cover a plurality of digits of one hand of a user.
3. A device according to claim 1 , in which the projector member(s) is/are fastened to the stand in such a manner as to project the test pattern towards a distal end of the fingers.
4. A device according to claim 1 , in which the test pattern comprises uniform lighting in one of the colors and repetitive light patterns in one or more other colors.
5. A device according to claim 1 , in which the system uses a uniform lighting device in one color and a projector member for projecting a test pattern in one or more other colors.
6. A device according to claim 4 , in which the uniform lighting is in green and the repetitive light patterns are in red and in blue.
7. A device according to claim 4 , in which the repetitive light patterns are squarewave or sinewave curves.
8. A device according to claim 4 , in which the squarewave or sinewave curves extend perpendicularly to the direction of movement and present a non-zero angle with the sighting axis of the acquisition systems.
9. A device according to claim 1 , in which the stand includes a member for guiding the movement of the user's finger.
10. A device according to claim 9 , in which the guide member comprises translucent screen that extends over one side of the acquisition zone remote from the optical acquisition member, and that includes at least one finger positioning mark.
11. A device according to claim 9 , in which the guide member is provided with an element for indicating a predetermined speed of movement.
12. A device according to claim 1 , including a lighting member in the near infrared and an infrared optical acquisition member connected to the processor unit to transmit thereto an infrared image signal, and the processor unit is arranged to extract from the infrared image signal an infrared image revealing a venous network of the finger.
13. A device according to claim 1 , in which the plane of the acquisition zone is inclined relative to the horizontal.
14. A device according to claim 1 , in which the processor unit is arranged to generate from the texture and the shape of the portion of the hand a rolled-out image representing the image of a fingerprint having the same resolution at all points.
15. A device according to claim 1 , comprising at least a second optical acquisition member, the optical acquisition member being positioned for increasing the area of the hand that is imaged.
16. A device according to claim 15 , wherein the optical acquisition members have optical axis forming an angle less than 45° approximately.