You may want to search for images that can be used in your own artwork. There are websites like Shutterstock that have costly images for sale, but did you know that there are Creative Commons websites that allow you to use images for free? Many of the creators of these images have given permission for artists to use their works--all you have to do is to give credit to their contribution. The following page will describe ways to locate Creative Commons images. Another page will show you how to cite them (MLA Citation).
Creative Commons is a licensing movement that allows the use of copyright works under specific licence terms. Creative Commons works are free for use as long as the terms of the license compiled with.
Creative Commons works are bound by licence restrictions, the main restrictions of Creative Commons licences are:
You let others copy, distribute, display, and perform your copyrighted work - and derivative works based upon it - but only if they give you credit.
You let others copy, distribute, display, and perform your work - and derivative works based upon it - but for noncommercial purposes only.
No Derivative Works means:
You let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it.
Share Alike means:
You allow others to distribute derivative works only under a license identical to the license that governs your work.
You may wish to use the Creative Commons search. To access this, please click the link above. The search will allow you to conveniently look at many CC websites at once.
You are probably used to searching in Google Image search for your images. You can still do this AND get Creative Commons images. Just search for what you're looking for, then click Search tools and the options are under "Usage Rights."
The US Government has millions of photographs and images that are free for public use--we essentially pay for these with tax dollars. The following list is made up of government websites with images.
Cartoon from the Library of Congress' Herbert L. Block Collection