Funny I saw this photo, I was studying for a test on lighting at the same time.
Some facts about light intensity for the nerds out there-
If the candle was 1 foot (12 inches) from the wall, the brightness (or 'Illuminance') is said to be 1 foot candle. The light coming from 1 candle is 1 candle power
What's interesting is what happens when the candle moves away from the wall. The intensity of the light decreases by 1/4 for each doubling of distance, so say the intensity level is 100% at 1 foot away, it is 25% at 2 feet away, and 11% at 3 feet away....
Light intensity = light output at source/(distance x distance)