Google Images offers a few special syntaxes:

intitle:

Finds keywords in the page title. This is an excellent way to narrow down search results.

intitle:paramecium

filetype:

Finds pictures of a particular type: JPEG, GIF, or PNG. Note that searching for filetype:jpg and filetype:jpeg will get you different results because the filtering is based on file extension, not some deeper understanding of the file type.

filetype:jpg paramecium

inurl:

As with any regular Google search, inurl: finds the search term in the URL. The results for this one can be confusing. For example, you may search for inurl:cat and get the following URL as part of the search result:

www.example.com/something/somethingelse/something.html

Hey, where’s the cat? Because Google indexes the graphic name as part of the URL, it’s probably there. If the page above includes a graphic named cat.jpg, that’s what Google is finding when you search for inurl:cat. It’s finding the cat in the name of the picture, not in the URL itself.

inurl:cat

site:

As with any other Google web search, site: restricts your results to a specified host or domain. Don’t use this to restrict results to a certain host unless you’re really sure what’s there. Instead, use it to restrict results to certain domains. For example, search for football.site:uk and then search for football.

site:com is a good example of how dramatic a difference using site: can make.

site:amazon.com shakespeare