Backlinks for my wordpress blog - queston

Someone posted a backlink on my blog, but he didn't link directly to his website, instead a picture of some person, which was still uploaded within his domain. It got me thinking, because his blog had a PR of 4.

Does this count as a normal backlink, or is it better to link directly to the main domain name? Or is it all the same?

This makes me think if that person is trying to rank that picture in google images.. ?

The image was also posted on one of the main pages of his website.