Just surround the craters with rings of soft lighting, do some random dithering around and between those rings (you could also dither with one shade darker), and that should be it. Make sure it tiles if you need it to.
Just surround the craters with rings of soft lighting, do some random dithering around and between those rings (you could also dither with one shade darker), and that should be it. Make sure it tiles if you need it to.