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I haven't done the math, but seeing the chapels in Cappadocia, Turkey seems to prove this. Most of the chapels contain frescoes that are significantly color-faded, but Karanlık Kilise ("Dark Church"), which is quite dim and has very little ambient light, contains frescoes with far richer color. [1]

Unfortunately, the guards stationed there like to yell at tourists even if their flashes are off, so I suspect most people don't understand the reasoning.

[1] http://en.wikipedia.org/wiki/Churches_of_G%C3%B6reme