Images are subject to the same copyright and fair use laws as written materials, so here too you’ll want to think about the fair use factors that might apply.
Is the image used in a transformative way? Are you taking only what’s necessary to convey your point? A thumbnail (reduced-size) image, or a portion of a larger image is more likely to be fair use than taking an entire full-size image. If you want to go beyond fair use, look for Creative Commons licensed images.
Posted in: Questions About Copyright