When doing identifications, I make extensive use of the keyboard shortcuts. I love being able to zoom in to the photo, but I often find that the photos are too dark, necessitating that I use the mouse to brighten them. This slows down what could be a smoother experience for doing a lot of ID’s.
I personally have only ever had to brighten an image, but you’d probably want both available.
Perhaps Alt/Cmd + ↑ to increase brightness and Alt/Cmd + ↓ to decrease brightness