You can use a library image database. You can click on the "Databases by Format" link below and choose "Images" under the "Format" drop-down menu. You might try ARTStor, searching for terms that you're interested in viewing.
Another resource you might consider is Flickr, which has photos that are Creative Commons-licensed. Be sure to tick the "Only search within Creative Commons-licensed content" checkbox when searching Flickr. Creative Commons has its own search tools. Both Flickr and CC are linked below.
