Re: Optical Density ?
Re: Optical Density ?
- Subject: Re: Optical Density ?
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Wed, 04 Sep 2002 10:17:34 -0500
David Harradine wrote:
>
As I understand the optical density scale there is no denser a d-
>
max than 4.
Density, D, is defined as:
D = -log10(Y)
Where Y is the relative transmittance (for transparent samples) or
reflectance (for reflective samples). So, by way of example:
Y D
------- ---
1.0 0.0 (100% of light is transmitted or reflected)
0.1 1.0 (10% of light is transmitted or reflected)
0.01 2.0 (1% of light is transmitted or reflected)
0.001 3.0 (0.1% of light is transmitted or reflected)
0.0001 4.0 (0.01% of light is transmitted or reflected)
0.00001 5.0 (0.001% of light is transmitted or reflected)
etc.
0.0 infinity (0% of light is transmitted or reflected)
Whether a scanner sensor or an instrument can actually measure very small
amounts of light is another story, but in theory, density values can go
infinitely high.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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