Presentation attack detection

Abstract

An apparatus for capturing an image of an object on a platen and including a platen having a surface for receiving the object, wherein the platen is transmissive to an optical wavelength of light, an illumination module configured to illuminate at least a portion of the object with light from an illumination source, and an optical sensing module configured to receive the light from the illumination source after the light interacts with the at least a portion of the object. The light from the illumination source is spatially patterned prior to reaching the object. The illumination module can be configured to create the spatially patterned illumination and/or the platen may include a patterned optical coating creating the spatially patterned illumination. The spatially patterned illumination can include a plurality of discrete areas (e.g., a stepped pattern) of different illumination intensity and/or a gradient of different illumination intensity.

1 . An apparatus for capturing an image of an object on a platen, the apparatus comprising:
 a platen comprising a surface for receiving the object, wherein the platen is transmissive to an optical wavelength of light;   an illumination module configured to illuminate at least a portion of the object with light from an illumination source; and   an optical sensing module configured to receive the light from the illumination source after the light interacts with the at least a portion of the object;   wherein the light from the illumination source is spatially patterned prior to reaching the at least a portion of the object.   
     
     
         2 . The apparatus of  claim 1 , wherein the illumination module is configured to at least partially create the spatially patterned illumination. 
     
     
         3 . The apparatus of  claim 2 , wherein the illumination module comprises a patterned object with spatially varying differences in at least one of optical transmission or reflection for at least partially creating the spatially patterned illumination from the light from the illumination source. 
     
     
         4 . (canceled) 
     
     
         5 . The apparatus of  claim 1 , wherein the illumination module is configured to dynamically change a pattern of the spatially patterned illumination. 
     
     
         6 . The apparatus of  claim 1 , wherein the platen comprises a patterned optical coating at least partially creating the spatially patterned illumination. 
     
     
         7 . The apparatus of  claim 6 , wherein optical transmission of the coating varies as a function of position across the platen. 
     
     
         8 . The apparatus of  claim 1 , wherein the illumination module comprises a lightguide comprising one or more structured areas that direct light toward the platen to at least partially create the spatially patterned illumination. 
     
     
         9 . The apparatus of  claim 8 , wherein the one or more structured areas comprise one or more of a reflective mirror, hologram, diffractive element, or ground or rough area of material. 
     
     
         10 . The apparatus of  claim 8 , wherein the one or more structured areas are electronically switchable. 
     
     
         11 . The apparatus of  claim 1 , wherein the spatially patterned illumination comprises a plurality of discrete areas of different illumination intensity. 
     
     
         12 . The apparatus of  claim 11 , wherein the spatially patterned illumination comprises at least three discrete areas of different illumination intensity. 
     
     
         13 . The apparatus of  claim 12 , wherein the spatially patterned illumination comprises a stepped pattern of discrete areas of different illumination intensity. 
     
     
         14 . The apparatus of  claim 1 , wherein the spatially patterned illumination comprises a gradient of different illumination intensity. 
     
     
         15 . The apparatus of  claim 14 , wherein the gradient is one of ramped or sinusoidal. 
     
     
         16 . The apparatus of  claim 1 , wherein the spatially patterned illumination comprises wavelengths of different color. 
     
     
         17 . The apparatus of  claim 1 , wherein the optical sensing module is configured to detect image data corresponding to different color wavelengths. 
     
     
         18 . (canceled) 
     
     
         19 . The apparatus of  claim 1 , wherein the optical sensing module comprises a color filter aligned to a sensor pixel array. 
     
     
         20 . The apparatus of  claim 19 , wherein the color filter comprises a pixelated color filter. 
     
     
         21 . The apparatus of  claim 19 , wherein the color filter comprises a plurality of selectable filters, each mechanically moveable into and out of an optical path of the sensor pixel array. 
     
     
         22 - 24 . (canceled) 
     
     
         25 . A method for detecting whether an object is a portion of human skin, the method comprising:
 receiving the object at a platen, wherein the platen is transmissive to an optical wavelength of light;   illuminating at least a portion of the object with light from an illumination source, wherein the light from the illumination source is spatially patterned prior to reaching the at least a portion of the object; and   receiving light from the illumination source at an optical sensing module after the light interacts with the at least a portion of the object.   
     
     
         26 - 36 . (canceled)