The handout & presentation (found below) on image copyright may serve as a point of reference when deciding how to use an image for academic purposes.
SBU Libraries pay subscription fees to several electronic database vendors, which also provide access to images. While you still need to credit the source that you retrieved an image from, images found in these databases may be used for academic purposes.
There are several Web sites that provide free access to images. This does not mean that you can use the images without crediting the source in a presentation or research paper for class. For more specifics on citing and determining image copyright policies, check out the PowerPoint presentation, which is available in the box located to the left labeled "Free Images & Fair Use."