Perception of luminance levels

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Tony Adams - 29 Sep 2006 15:41 GMT

Hi,

I have an interest in photogryphy and would like to know if anyone
could help solving the following question: Is it true that the eye
distinguishes fewer luminance levels in the dark areas of a print due
to visual interference from the light areas than in the brighter ones
and that the number of luminance levels that the eye can distinguish
decreases in general gradually from light to dark zones? If so, does
anyone have some quantitative measures at hand as to how this
perception decreases? - As prints are normally viewed under daylight,
we surely have to consider only the light adapted status of the cone
system here.

Best regards!
Tony Adams

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Liz Day - 30 Sep 2006 19:07 GMT

>Is it true that the eye
> distinguishes fewer luminance levels in the dark areas of a print due
> to visual interference from the light areas than in the brighter ones

I don't know, but you might be able to tell by getting a picture with a
lot of shadow detail and masking all the light areas off with a piece
of cardboard, then seeing if you can see more levels of grey in the
dark areas when the cardboard is on than when it's off.

> and that the number of luminance levels that the eye can distinguish
> decreases in general gradually from light to dark zones?

You might try this question of the Photoshop list - worth a shot.
http://www.listmoms.net/lists/photoshop/

LD

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