What sort of optical illusion trickery is this? Photographer reveals secret behind his cute "Honey, I shrunk the dog" photo

White dog on grass lawn with giant yellow tennis ball.

Social media and the internet is full of faked photos. I would say it’s hard to spot what’s a real photo and what’s been given the AI treatment, but often it’s fairly obvious. However, when I posted this photo of our dog next to a tennis ball, I was met with confused responses. 

“How’d you make your dog so tiny, Peter?”