1. A computer-implemented method for training a deep learning neural network for compact face representations, the method comprising: presenting face images to the neural network; the neural network processing the face images to produce compact representations of the face images, wherein the compact representations have not more than 64 dimensions; processing the compact representations to produce estimates of a metric, for which actual values of the metric are known; and training the neural network based on the estimates of the metric compared to the actual values of the metric.