I think you are right about the "infinite scale" thing but also that the bit count is correct up to a multiplication coefficient, given a specific resolution yo

I think you are right about the "infinite scale" thing but also that the bit count is correct up to a multiplication coefficient, given a specific resolution you are trying to achieve. To put it in mathematical terms, there is no reason to use the log base 2, but the formulae is definitely a logarithm. So, again, 20 bits is a minimum bit count conveniently used to compare with others situation (e.g. "if you are shooting not in direct sunlight, you will only need 12 bit minimum, not 20 bit minimum so this method of shooting is OK") and make decision about your color pipeline You will need 20 bits if a human can distinguish 1,000,000 levels between those two extremes It's not about what we can perceive but how we store and manipulate amount of lights in our pipelines