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From: alanr@dd.eng.bbc.co.uk (Alan Roberts)
Subject: Re: Are 24-bit video adapters toys?
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Date: Tue, 25 Oct 1994 13:41:14 GMT
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: bryant@neural.Kodak.COM (Steve Bryant) writes:

: >In fact, my colleague here says that he has read research articles stating
: >that the eye is not capable of resolving less than 3 parts in 256. Granted,
: >this is pure hear-say evidence and I dont have the reference to the article,

: One could perhaps have a flare model of the CRT and use that then during
: the viewing to compensate the loss of contrast. The viewing program
: would first estimate whether it can view the requested contrast or not
: and then try to make best out of the situation. This approach could
: also easily compensate dark corners of the CRT.

The considered opinion of the world's broadcasters (EBU, ABU, SMPTE et al)
is that the human eye can struggle to resolve a brightness difference of
about 1%. That means _within_a_picture_. There is no point providing
contrast of greater than 100:1 within a picture because the eye responds
to the mean (or possibly weighted peak) brightness and adjusts its gain
accordingly. Greater contrast means that the blacks gets darker, and below
1% the eye [produces no response from them. If you increase (or reduce)
the overall brightness, the perceptible contrast range will remain at
about 100:1. It is limited by flare in the lens, and by internal reflections
within the eye.

--
************* Alan Roberts **************
* BBC Research & Development Department *
* My views, not necessarily Auntie's    *
*    but they might be, you never know. *
*****************************************
