If you want to correct the laptop screen brightness, install xbacklight:

Set up sources file(s):
Add or activate repos main, contrib and non-free
$ sudo nano /etc/apt/sources.list
Update repos:
$ sudo apt-get update
Install the application:
$ sudo apt-get install xbacklight
Test the xbacklight support:
$ xbacklight -get
Set Brightness to 00%:
$ xbacklight -set 00%

To add the program to the system boot up in Gnome:
Add the command to Applications > Main menu
Add the command made with the main menu to Applications > Tweak Tool > Startup Applications

References:
File: xbacklight _ Corregir el brillo en linux _ Yo amo la informática.pdf

Issues:
Xbaclight does not work in all laptops.

Cairo-Dock:
For the brightness adjustment to work you require Gnome Desktop or Xbacklight, but if they won't work try installing Cairo-dock app and when the apps dock is ready make right click on it, and then go to menu configure and then add Luminosity. Luminosity is going to change the screen Brightness not only in Laptops but also in Desktop computers.
References:
Guide: Cairo-dock