Eg knowing that the input was black text on white background or a natural image (instead of eg white noise) helps a lot.
Machine learning can also do a surprising good job of it, especially if you know what the target is (e.g. a face) https://www.vox.com/future-perfect/2019/9/4/20848008/ai-mach...
Sample code: https://gist.github.com/JonathanFly/80b669a72bf624d17b56a1cf...
Yes. Though that's just a corollary of doing better when you know something about the probability distribution of inputs.
(But a very useful and practical corollary. My formulation didn't give any hint how you might make use of that knowledge of the distribution.)
Eg knowing that the input was black text on white background or a natural image (instead of eg white noise) helps a lot.