The image can have two or three "bending styles", horizontally or vertically and may start in a bent or not bent state. On IOS, just tap once, to change "states." This starts in a three bending style state, straightens out with mouse hover or IOS tap. Returns to bend state when mouse moves away from bent image or IOS taps elsewhere.
Or you can start with no bends, and hovering the mouse causes the effect. The bendable portion can also be linked, but on IOS it will quickly go to the link, and you may blink and miss the change of state to the bendable object. This Mount Ranier images does not have a link so that IOS devices may tap and cause the image to flatten out.
Another Lake Chabot image with a link to Wikipedia and purple to brown gradient overlay.