Is there such a thing as meta tagging graphics on a web page?

I've been doing some web work for a client and they've asked me to meta tag images on their web page with some 开发者_如何学Pythonspecific data, I've not heard of meta tagging images, at least not using standard html before and a quick search reveals that there isn't a standard meta tag for this. However I did notice facebook OpenGraph protocol but I'm pretty sure that's not what he wants.

Has my client been ill informed about something or am I missing something?

If the images are JPEG then you can store meta data using EXIF.

That said, you should probably find out what your client wants to achieve with the meta data and solve that problem.