If the images are public domain (and I would think they must be by now), then the blanket statement should be fine. If you get the images from a website, the website may have stipulations about how their images may be used and how to cite. I am not certain that something being on Wikimedia Commons automatically means it's public domain, so see what their fine print says.
"Our aim in Education is to give a Full Life." -- Mom to 4 AO Graduates, Grandma to 3
"Practically, nearly, almost and in all ways visible to normal mortals Invincible" (due to the diplomatic immunity of Admin.)
"Practically, nearly, almost and in all ways visible to normal mortals Invincible" (due to the diplomatic immunity of Admin.)