Anyway to restrict the selection of file types via the element?
For instance, if I wanted only images types to be uploaded
There is an html attribute for this specific purpose called accept but it has little support across browsers. Because of this server side validation is recommended instead.
If you don't have access to the backend have a look at a flash based solution like SWFUpload.
See more on this here: File input 'accept' attribute - is it useful?