After the Renaissance, Muggle paintings often used the effect of "perspective," which was based on the increasing distance between an object and the observer.
When an object was far from the observer, it looked small; as one kept approaching it, it gradually grew larger. When the distance was great enough, even a star was no bigger than the tip of a needle, while at close enough range, even a real needle looked larger than it.
Pomona and Filius trudged through the Forbidden Forest together, stumbling over uneven ground. Human Snape walked ahead of them, his strides so large that neither of them could keep up.
Because of the effect of perspective, there seemed to be another world behind the painting. When Bill had been breaking the curse, he had thought the Death Eaters had used an advanced Extension Charm on the painting, which had sent him on quite a few detours.
As Muggle technology developed, the way they recorded images changed, with photographs replacing portraits. Wizards used them too, except wizarding photographs could move, endlessly looping the same repeated scene: dancing in an autumn forest blanketed with fallen leaves, for example, or, like Gilderoy Lockhart, constantly showing passersby his award-winning smile.
These photographs could not interact with people outside as portraits could, even though there also seemed to be another world within them.
"So Phoebe went blind back then not because her eyes had turned into 'paint' too?" Pomona asked Flitwick.
"Human Transfiguration comes in many forms." Flitwick tugged at the robe caught on a bush. "I thought that, as Headmaster Dumbledore's student, you knew even more than I did."
If she had not spent so much energy and time practicing culinary magic.
Pomona thought this as she looked at Snape's dark back ahead of her.
Although Human Transfiguration was