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From: rick@hanauma.stanford.edu (Richard Ottolini)
Newsgroups: comp.graphics
Subject: Re: Colours
Message-ID: <6641@portia.Stanford.EDU>
Date: 14 Nov 89 17:08:59 GMT
References: <1989Nov14.090210.22777@jarvis.csri.toronto.edu>
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Reply-To: rick@hanauma.UUCP (Richard Ottolini)
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Organization: Stanford University, Dept. of Geophysics
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Someone asked are 64 gray levels enough?
The answer depends on the spatial freqeuncies and correlation scales in the
image data.  Rapidly changing image data can get by on as little as 16 levels
(e.g. geophysical seismic data) while low frequency changes may need 7 or 8 bits
(e.g. Landsat images).  This result has been known to perceptual psycologists
a long time (e.g. Landsat images).  A quick test is to blink between two quantization
images and see if you detect a difference.