How to achieve this noise/grain-like effect?

[ledshok]

Any tips on how to achieve the noise/grain effect below?

I don't think it's actually noise as you can see that some of the larger 'chunks' of noise correspond to blemishes on his skin eg the small dot under his left eye results in a distinct black bit of noise in the final image. So presumably they've used a filter to 'detect' these darker bits, made them very constrasty, then overlaid them on the original image (since, under the noise, you can still see the greyscale skin tones).

But as a Affinity Photo newbie, I'm a bit lost.

Thanks in advance for any tips/suggestions!

Before image:

After image:

[NotMyFault]

The tone map persona can be used.

maximize local contrast, and play with black point.

reduce saturation to zero.

you may need to add a curves adjustment later.

[ledshok]

Oh, this is exactly what I'm after - thank you so much! 😀