Legaly they canot take your site or domain unless you are using their script, or selling it or doing the same thing they are.
The sites do not have the same function and could not be confused.
You should check the TM and see the services they have TM'd under. They probably registered it as a web scripting company. Then you are safe as a image host.
If adding words would violate TM's then every short 1 word.com would be able to take any name that is using their word in it. And that will not happen.
Also remember TM is not registered with anything, its just 2 letters you use to represent you are doing bussiness with that logo/word(s). Only when you see the "R" icon is it a legal TM. And even then it only applies to 1 or a few fields of bussiness, not all.