How can I tell if a picture is taken from the internet?

-My friend sent me a drawing that was way to good to be them. it was the most amazing artwork ever, and they said that they drew it, is there a way, I can take the image, and see if it is somewhere else on the internet?Or ask them to retake with a distinguishable and unique item in the pic as well.

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Edit:

Well, if that's the case, you could ask if he could make a collage out of it w/ other interests included, (Profile pic?) or maybe a picture of it framed on the wall, or something similar.

Just little things like that.

Or something simple, like,

"How big is the pic? How's it look on your desk?"

Stuff like that.



Thanks :) Your idea was cool too. I use a few things like that myself.