How do I adjust screen luminosity

[Littlechay]

for  open cpn push "c" or "view" and change color scheme .
or on the display its self  "manual solution"

F5, F6 & CTRL+G in OCPN are the colour scheme and brightness controls. 

https://opencpn.org/wiki/dokuwiki/doku.p...navigation

Otherwise at system level in the PI

Need to be su for some reason

Code:

sudo su

The driver for the screen provides an interface through /sys/. To turn the screen on you can use the command:

Code:

echo 0 > /sys/class/backlight/rpi_backlight/bl_power

and to turn it off:

Code:

echo 1 > /sys/class/backlight/rpi_backlight/bl_power

the brightness can be adjusted using:

Code:

echo n > /sys/class/backlight/rpi_backlight/brightness

where n is some value between 0 and 255.