# How can you have a scene linear reflectance greater than 100%?

Started 3 months ago | Questions thread
Re: Fluorescence

Interesting. So what about the claimed 90% reflectance for white paper? Also, why use optical brighteners to begin with?

It's just that it's so unintuitive having reflectance percentages greater than 100%(in this case going all the way up to 1400%-ish in the graph) as it doesn't really make sense(you can only reflect a 100% of light). Perhaps, as someone alluded above, it has to do with diffuse and spectral reflectances and even incident and reflectance all being considered together in 1 graph.

I' m gonna try and explain this conundrum with an example. Imagine we have a frame where we are OUTSIDE and we can see:

-The sun at noon(Incident)

-Clouds(reflects)

-A caucasian person(reflects)

-White Paper(reflects)

-18% middle gray card(reflects)

Now in many measurements the clouds(especially ones close to the sun) will have a reflectance % significantly above 100%, whereas white paper will be somewhere 90-100% but the problem is they're both being lighted by the sun thus have the same amount of light falling on them. So if a sun is giving out an X amount of light it doesn't make sense that white paper will reflect 0.9X,18% gray will give 0.18X, whereas the clouds will be anywhere from 2X-30X(Just making up random numbers here) you can't reflect more than X itself(I.e above 100% reflectance) is what's tripping me up.  Hope I managed to explain myself. Perhaps the individual who made LUTCALC is using some standard that I'm unaware of.

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