  Face hallucination, which is the task of generating a high-resolution face
image from a low-resolution input image, is a well-studied problem that is
useful in widespread application areas. Face hallucination is particularly
challenging when the input face resolution is very low (e.g., 10 x 12 pixels)
and/or the image is captured in an uncontrolled setting with large pose and
illumination variations. In this paper, we revisit the algorithm introduced in
[1] and present a deep interpretation of this framework that achieves
state-of-the-art under such challenging scenarios. In our deep network
architecture the global and local constraints that define a face can be
efficiently modeled and learned end-to-end using training data. Conceptually
our network design can be partitioned into two sub-networks: the first one
implements the holistic face reconstruction according to global constraints,
and the second one enhances face-specific details and enforces local patch
statistics. We optimize the deep network using a new loss function for
super-resolution that combines reconstruction error with a learned face quality
measure in adversarial setting, producing improved visual results. We conduct
extensive experiments in both controlled and uncontrolled setups and show that
our algorithm improves the state of the art both numerically and visually.
