Ambient light range for dimming TFT display

[ricko_uk]

Hi,
what are the min and max lux values for ambient light useful to determine the backlight brightness of a TFT display?

i.e. the min lux value for a low-light room where you can set the backlight to a minimum and a lux level at which you would start setting the brightness to the maximum?

Thank you

[ajb]

Well, the minimum ambient lux value could be zero, if the display is the only light source in the room, to 130,000 lux if it's used in direct sunlight.  Narrowing the range down at all depends a lot on the application.  Something like a radio that might be used in a bedroom at night would need a very deep-dimming backlight, but an industrial control panel used in a brightly lit factory won't need nearly as much range.  Plus the optimal backlight level will depend on other factors than just the incident flux, like the direction that flux is coming from, whether the front of the display is glossy or matte, and what's in the visual field around the display. 

[ricko_uk]

Thank you ajb