A trial version is available: https://play.google.com/store/apps/details?id=com.out386.underburn.trial

Ever had someone send you a white image at night, or had to open a browser, while using a dark theme? No need to fumble for that brightness control any more, Underburn will reduce the brightness for you!
Unlike other brightness apps, Underburn dynamically sets your screen brightness based on what's showing on your screen, not the ambient light level. This relieves stress when opening light images/apps when using a dark theme at night, without making the brightness so low that the dark theme is invisible. Once you're back on a dark screen, the brightness will go back up.
Response times are low, so even if you're scrolling a dark page, and a light image scrolls into view (think dark messengers), Underburn has you covered. What's more, you don't even need to be rooted!

Performance impact:
Almost none. Barely noticeable CPU usage, and negligible battery usage. Underburn is very optimized.

Extra features:
* Locale/Tasker/Automate (and others) support. Set brightness values and start/stop automatically
* Quick Settings tile for Nougat and up
* A floating brightness slider to quickly adjust brightness from any app
* Notification buttons for quick controls
* Screen dim filter
* Time-based and app-based schedulers

Compatibility:
* Lollipop to Oreo
* Adaptive brightness will be disabled while Underburn is running
* Screen casting will not work when Underburn is active; you'll have to stop Underburn
* No root required

Permissions:
* Record screen: Needed to constantly check the colors of what's on the screen
* Write settings: Needed to set the device brightness
* Draw Over Other Apps (optional): Needed to show the floating brightness button on screen, if you want it
* Receive Boot Completed: Used to start the service on boot
* Vibrate: Used for feedback when the floating button is long-pressed
* Usage Access (optional): Needed for App Profiles, if you use it

No data is ever collected, stored on your device, transmitted, or abused in any way. Underburn doesn't even have any analytics (beyond Google's statistics), or the permissions needed to access the Internet.


Play listing image credits:
Edho Pratama
Mingwei Li