From photographs to usefull 3D assets.
What are they good for?
With proper PBR textures, you can get a way with having a lot less detail on your geometry. The holes in this blanket are simply alpha maps that tell the renderer to be transparent where the image is black.
There are various techniques for generating the additional maps needed to control transparency, specularity and roughness. Usually though the latter two will require either some manual color manipulation or some hand-painting. In this case I was able to adjust the levels of the original photograph enough to produce the alpha map you see here.