Attributions

I am working on a project where I have downloaded images from a subscription service.  As I understand it I am obliged to show attributions for each image.  Does anybody have an idea of how to do this without muddying up the appearance of the graphics?  Can I put an attribution slide at the end of the module?  Is there some particular format I should use that keeps within the spirit of the agreement with the subscription service yet doesn't make my project look like junk?