EDIT: Updating to Ubuntu 13.10 solved this issue for me out of the box.

I'm trying to get some control over the brightness of my Samsung QX411 (Integrated Intel graphics) on Ubuntu 3.04 (though I have the exact same issue on 12.04 and on Mint)

Using FN+up/down lowers the screen brightness from max to one peg down or back up. If I try to bring the brightness down any more, it flickers but stays the same.

I have full control of the brightness in Settings, but that's delicate and gets reverted to full max if I open up the brightness settings again, use fn+up/down, the screen goes into power saving, or after log out.

The closest I got was adding

acpi_backlight=vendor

to a line in /etc/default/grub, [source]

I could consequently lower the brightness a couple of pegs down to the minimum with FN+down, but then it's as if the problem got inversed, and I'd get stuck in the bottom tier, I could only increase the brightness by one peg and back down. Rebooting would revert to max brightness.

Adding

acpi_osi=, acpi_osi=Linux, acpi_osi=vendor, acpi_osi='!Windows 2012', acpi_backlight=Linux, acpi_backlight='!Windows 2012'

instead didn't do anything for me.

I've also tried adding

echo 2000 > /sys/class/backlight/intel_backlight/brightness to /etc/rc.local,

where my max value from cat /sys/class/backlight/intel_backlight/brightness is 4648, which didn't do anything. (same result with echo 2000 > /sys/class/backlight/acpi_video0/brightness) source

Samsung tools also didn't help in this regard.

I've spent days on this, it's getting quite frustrating. Any help would be greatly appreciated.