Re: Using gamma 1.0
Re: Using gamma 1.0
- Subject: Re: Using gamma 1.0
- From: Don Hutcheson <email@hidden>
- Date: Mon, 24 Sep 2001 23:58:51 -0400
As a wild guess (without actually looking up the site) I'd say that site is
probably talking about 'gamma 1.0 photography' - something completely
different from a gamma 1.0 profile.
Gamma 1.0 photography is an old concept whereby the photographer uses
pre-exposure masks and/or modified exposure and development techniques to
capture the original scene with an approximately 'linear' contrast on film.
Here the use of the word 'gamma' refers to the slope of film's
exposure-density curve. Most films reproduce the scene with exaggerated
contrast, or a slope (gamma) of about 1.5. The point of gamma 1.0
photography is to reproduce scene brightness variations as nearly identical
brightness variations on film.
An ICC profile with a gamma of 1.0 is unlikely to do anything good at all,
as here the gamma number refers to something completely different, namely
the distribution of digital values (nominally 0-255) versus visual
lightness. The ideal distribution of lightness units approximately equates
to a profile gamma of about 2.8.
Don
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