I'll put this in books but I might end up finding what I need on a website. Fingers crossed for book recommendations.
When you read about a very famous historical figure, often the writer will talk about the significance of a particular portrait e.g. the jewelry the person wore, or the artist who painted it, or why it was commissioned. What the message of the piece was. You can build up a mental catalogue comparing and contrasting the various depictions of the person and what they all mean. Is there a name for this? Is this something people study? Is it a branch of history of art, maybe? I imagine that surely it must be!
I am asking because I have fallen down a couple of rabbit holes, reading about some lesser known historical figures and when I google to see images of paintings of them I want to know why, when, by who etc. I could look up each piece individually, but there is often not much information available, and my prior knowledge isn't enough to make it meaningful.