A method for distinguishing a real three-dimensional object from a two-dimensional spoof of the real three-dimensional object, the method comprising: obtaining, by an optical sensor of a mobile device, an image containing an object that is either the two-dimensional spoof or the real three-dimensional object; providing the image to a neural network; processing the image by the neural network by calculating: 1) a distance map representative of the distance of pixels to the optical sensor, the pixels constituting at least a portion of the object within the image, or 2) a reflection pattern representative of light reflection associated with pixels constituting at least a portion of the object within the image; comparing the distance map or the reflection pattern with a learned distance map or a learned reflection pattern; and obtaining as a final output a determination the image contains either the two-dimensional spoof or the real three-dimensional object.