[Leica] How digital noise is different from film grain (my bestdescription)

[bdcolen at earthlink.net (B. D. Colen)]

Absolutely - And that then requires either using one of the
noise-removal programs, which can to quite a good job, or burning in
those shadow areas. But either way, it's quite different from dealing
with grain in a film image.

-----Original Message-----
From: lug-bounces+bdcolen=earthlink.net@leica-users.org
[mailto:lug-bounces+bdcolen=earthlink.net@leica-users.org] On Behalf Of
Adam Bridge
Sent: Tuesday, September 07, 2004 4:17 PM
To: Leica Users Group
Subject: [Leica] How digital noise is different from film grain (my
bestdescription)


Today I was spotting some black and white scans and the difference
between digital noise and film's grain leaped out at me.

In film, as you move into the blacks, they become denser and denser as
the grains converge. So blacks are black.

But in digital the noise happens IN the blacks - adding speckles of
light where there should be black or at least very dark. The worse the
noise the higher up the luminance values the effect becomes. So at 100
you see nothing in the very dark areas but by, say 400 there are subtle
flecks of brightness creeping while while at 1600 these effects are
moving well up into the mid-tones.

So when you look at a digital image or a film image there is a definite
quality difference between the way noise and grain operate in the dark
tones.

Adam
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