Is there any way to reduce minimum brightness without root?

I want to reduce the minumum brightness of the screen of my Toshiba Excite Pro tablet. This is a tablet which (as far as I can tell) is essentially impossible to root, but I want to change the brightness of the screen, the value of which is stored in a file in the /sys/ directory of the tablet's filesystem. I want to change the value stored in this file from "35", to, say "10". Is there any way I can do this? For example: - a way of temporarily getting permissions to alter this file without fully rooting the device - an app which does not require root which reduces brightness beyond the default minimum - or if there is, indeed a way to root this device now, that would be good. Note: I'm not looking for an app which will put a filter over the screen to darken it; I want to turn down the screen as it's the biggest consumer of energy and I want to increase battery life. Edit: I want to change this file as 35 is the *minimum* screen brightness. The system settings for some reason have a very narrow range of allowed brightnesses.