Watch any crime show on TV and eventually they will use a piece of software to “enhance” an image – e.g. zoom-in, deblur, remove noise. For example, enlarge and sharpen a blurred image of a person’s face to the point where it is crisp and identifiable. The reality is far from the truth though. This paper looks at the basic problems of enlarging images. Nonsense like zooming in, looking at images in reflections, and enhancing are only possible if the information is there.
That’s not to say facial recognition won’t work – it may work great if you have a gigapixel image, you can zoom-in to your hearts content. If you have a 2 megapixel image – good luck.