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Systems and methods for spoof detection based on gradient distribution

  • US 10,068,124 B2
  • Filed: 12/22/2016
  • Issued: 09/04/2018
  • Est. Priority Date: 11/10/2016
  • Status: Active Grant
First Claim
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1. A method for spoof detection, comprising:

  • receiving an input image of a biometric;

    generating a first filtered image by applying a first convolution to the input image based on a first convolution kernel;

    generating a second filtered image by applying a second convolution to the input image based on a second convolution kernel;

    computing a gradient residual image by subtracting, for each pixel location of the first and second filtered images, a pixel value in the second filtered image from a corresponding pixel value in the first filtered image;

    applying a density estimation procedure to the gradient residual image to identify areas of varied density; and

    determining whether the input image is a replica of the biometric based on results of the density estimation procedure,wherein applying the density estimation procedure comprises;

    for each pixel location of the gradient residual image, summing an amount of gradient present in a window around the pixel location to generate a density value of the window around the pixel location;

    computing an average density value of the density values of the windows;

    determining a count of a number of windows that have a density value that deviates from the average density value by a threshold amount; and

    identifying areas of varied density based on the count.

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