The best tool for image-related scholarly research is ARTstor. However, ARTstor has rules about how images can be used - you can use them in your homework, presentations, password-protected education websites (Canvas), and personal use (inspiration). You cannot post them on the open web or use them for profit.
To save or download images from ArtStor you must build an account while on campus. Click on "Enter ArtStor Digital Library" then use the "Log In or Register" link in the upper right.
The images found at these sites work well for art projects. Use them for research and scholarly papers only if you can verify that they are from a reliable source and have not been edited.
When using images for non-educational work, there are rules in place to protect the creator of the original image. The best thing to do is to find images through Creative Commons that allow modification.