I have noticed, that for keywords including the term "photo" or "picture", there are several websites only containing pictures and zero text, which can be found at top 10 positions.

Why is that so? Has google some kind of algorithm that searches especially for <image> tags when I use keywods including picture? I know it is not about the "alt" tags because most websites didn't even have "alt" tags...

Does anybody know more about this?

regards

Guido