How to create this kind of grain effect on photoshop? Tried gradient map, exposure and can't figure out what to do next. Here's the original one and result.
Grain can be got by adding noise (=Filter > Noise > Add noise). In this case you want to start by inserting lighter noise to dark areas, but not dark noise to light areas because the noise content on the background and on the person seem to be different. Noise on dark only can be got with a black layer which has 50% monochrome noise and blending mode ADD:
Now it's ready for extreme contrast boost with treshold adjustment layer:
It has still some apparent greys due the halftoning caused by noise density dithering. To make it negative a curves layer is inserted:
The black needs noise, too. Get it with another black layer (=a duplicate) which has blending mode Add:
Adjust the layer transparency. Here it's reduced to 59%.
Adjust the amount of the noise in light areas by changing the treshold:
Not a perfect copy, but at least it resembles the wanted effect.