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

Started 3 months ago | Questions thread
alanr0 Senior Member • Posts: 2,484
Re: How can you have a scene linear reflectance greater than 100%?

MrBrightSide wrote:

Those numbers from 0 to 720 look like mV values for the luminance channel. Is that what you’re asking about?

Anything is possible, but the OP is convinced they represent percentage reflectance values - possibly because that is how they are labelled on the screen shot.

The choice of 18% and 90% reflectance values seems significant. These numbers crop up in the ITU documents that spider-mario linked, including ITU report BT.2408-4, where they appear as widely used grey scale reflectance values. See for instance the figure here.

You could check out the gitbub repository for LUTCALC which I believe is the source of the graphic.  My guess is careless terminology for relative exposure values, but I have not dug deeper to find out.

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Alan Robinson

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