I created a 80-backlight.conf file according to the Intel HD Graphic Controllers section of page https://wiki.ubuntu.com/Kernel/Debugging/Backlight
and then the brightness script is now working, but it does not improve the brightness farther.
Probably I got used to the high brightness and brillance of an LCD monitor I am using as an external display.
It must be the lower screen quality of the labtop display which made think of a backlight bug.
I created a 80-backlight.conf file according to the Intel HD Graphic Controllers section of page /wiki.ubuntu. com/Kernel/ Debugging/ Backlight
https:/
and then the brightness script is now working, but it does not improve the brightness farther.
Probably I got used to the high brightness and brillance of an LCD monitor I am using as an external display.
It must be the lower screen quality of the labtop display which made think of a backlight bug.
This ticket can be closed.
Sorry for annoyance.
Nicolas