I don’t know if Instagram does this on all phones, but when I make multi-photo posts, it often leaves behind a very interesting image. Sometimes, the result is very artistic, such as this one of a Lotus–Ford Cortina Mk II.
You can see the rear three-quarter shot just peer in through the centre. I’ve a few others on my Tumblr, but this is the best one. Sometimes technology accidentally makes decent art. I’m still claiming copyright given it’s derived directly from my work.
PS., March 3: Here’s a fun one from my visit to Emerson’s Brewery.