Black Light is intended to modify your screen light parameters so that you can have a more comfortable experience when you are using your computer. Thus, the tool can directly modify the gamma curve to reach the expected results.
The application runs quite unobtrusively and is available from its icon on the Menu Bar. Moreover, it can be accessed from the Dock or with a hotkey combination. In this respect, all its effects can be activated from the Preferences window. Various effects are available. For instance, you can reverse black and whites or replace light gray pixels with white. Likewise, it can adapt HDMI output to the 16–235 luminance range supported HD televisions.
Other possibilities include dimming screen luminosity even beyond what is normally possible. There is also a color filter, which lets you change the screen tint. Likewise, you can set the effects to work on the current screen or all of them. Fortunately, you can save your profile if you intend to use it later.
Regrettably, Black Light cannot change the luminosity profile automatically according to the time of the day, except if Night Shift is also installed. It does not let you schedule color changes. It is also a shame that transitions occur all of a sudden as no gradual fading is allowed. Similarly, I would have liked to be able to use individual hotkeys for each effect.
All in all, Black Light can protect your eyesight by adapting your screen to different lighting conditions or times of the day. The product can be bought at different prices from the Apple App Store and the developer’s site, so you may want to check on that. It can be tried at no cost and there is a Pro version that solves some of the limitations described above.