Luminosity By Value Quiz

Evaluate the colour presented to you and attempt to determine a luminosity value between 0 and 255. Use integers; i.e. "5", not "4.9".
Simply input this number in the box and Click 'Guess!'. The histogram at the left is a Nikon example and is there for your reference.
Don't click the 'back' button on your browser to try again or the application won't keep score properly.