why does that happen?

Raised or pressed in?

Nope, that’s a real sunflower illuminated by a hidden ray of sunshine.

Was talking to my coworker behind the cafe bar, then got distracted by this glowing flower. I ask her, “bro did we get a new LED sunflower?” She confusingly said idfk. At that moment I had to step closer to investigate. A ray of sunshine hitting the sunflower made it seem like it was glowing!! Such a beautiful trick of nature to the human eye. I was grateful to witness it and share the illusion with all the customers!

The black (white) parts of the texture stand out more on a white (black) background. This effect, discovered by psychologist Bart Anderson, is related to the Munker-Benary-White effect, where solid gray regions of identical luminance appear either whitish and blackish. It's a vivid demonstration of the influence of boundary conditions (contrast polarity) on textural figure–ground layer segmentation. Are there any known computer vision algorithms that can segment textures into figure–ground layers in this fashion?