Have you ever been using your computer, outside, in the middle of the summer?
Being a former wedding DJ, I have spent many summer days outside, unshaded, with the hot sun rays shining straight on to the display of my computer. I had my display Brightness turned all of the way up, and I still couldn't see. Even worse, the music program I was using had a dark background, making it even more difficult to see. There is a work-around, however.
If you navigate on your Apple computer to System Preferences > Accessibility > Display, you will see a checkbox titled Invert Colors. What this does is takes all of the colors across your display and completely inverts them.
To make things easier, if you go into your System Preferences > Keyboard > Shortcuts, on the left margin you will see, again, the Accessibility option. Third from the bottom of the ensuing screen, you'll see a shortcut to invert the colors on your Mac. The shortcut is Control (⌃) + Option(⌥) + Command (⌘) + 8 .
This was huge for me. Now I could just enter a quick key command to invert my display colors, then once it was dark enough to see my screen again, I could invert it back. Here is the before and after.