Use Photoshop’s Lens Correction filter to remove darkened edges – mostly known as vignettes – in Photoshop
Sometimes a camera will capture images will an accidental vignette. Usually this is down to the quality of the lens, but can also appear naturally because of the lighting situation.
The Lens Correction filter under Filter>Distort contains a slider called Vignette. By pushing this to the right into the plus numbers, the edges of an image can be lightened up. This will counter any vignetting that’s not needed.