A biometric authentication system comprising: one or more processors configured to interact with a computer storage medium to perform operations comprising: generating, by applying a linear regression analysis, a data model of characteristics: (i) in a plurality of live images, each live image being taken directly of a portion of a body of any person and (ii) in a plurality of fabricated images, each fabricated image being an image taken of an image of a portion of a body of any person; obtaining, using the images, measurements of characteristics in each image, the characteristics having been selected using the data model; determining, based on a liveness function, a score for each image using the obtained measurements of the characteristics in the image; accessing, from the computer storage medium, a threshold value; comparing the score of each image to the accessed threshold value; based on the comparison of the score of an image to the accessed threshold value, determining, for each one of the images, whether the image is (i) a live image of a portion of a person's body, or (ii) a fabricated image of a portion of a person's body; determining whether a count of images containing a unique person satisfies a threshold count; and if the count of images containing a unique person satisfies the threshold count, deleting the measurements of characteristics that are determined to be irrelevant and regenerating the data model of the characteristics based on a second linear regression analysis. generating, by applying a linear regression analysis, a data model of characteristics: (i) in a plurality of live images, each live image being taken directly of a portion of a body of any person and (ii) in a plurality of fabricated images, each fabricated image being an image taken of an image of a portion of a body of any person; (i) in a plurality of live images, each live image being taken directly of a portion of a body of any person and (ii) in a plurality of fabricated images, each fabricated image being an image taken of an image of a portion of a body of any person; obtaining, using the images, measurements of characteristics in each image, the characteristics having been selected using the data model; determining, based on a liveness function, a score for each image using the obtained measurements of the characteristics in the image; accessing, from the computer storage medium, a threshold value; comparing the score of each image to the accessed threshold value; based on the comparison of the score of an image to the accessed threshold value, determining, for each one of the images, whether the image is (i) a live image of a portion of a person's body, or (ii) a fabricated image of a portion of a person's body; (i) a live image of a portion of a person's body, or (ii) a fabricated image of a portion of a person's body; determining whether a count of images containing a unique person satisfies a threshold count; and if the count of images containing a unique person satisfies the threshold count, deleting the measurements of characteristics that are determined to be irrelevant and regenerating the data model of the characteristics based on a second linear regression analysis.