Digital BW, The Print

----- Original Message -----
From: "flyfishingusa2002" <tflyfish@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Wednesday, April 24, 2002 12:23 AM
Subject: [Digital BW] Re: Densitometry Help


> John,
> You are at the same point as I am. Well, actually I'm a little
> ahead. The density readings are log to the base 10 so dividing the
> Dmax by 2 will not give you the expected 50% reading. I am currently
> trying to figure out the math.
> I will let you know when I get there,

Every 0.30 is double or half the previous reading thus if 0.0 density = 100%
transmission (you should be so lucky) - 0.3 density =50% - 0.6 = 25% - 0.9 =
12.3% which is why 1.0 = 10% - 2.0 = 1%  (i.e.100-1 ratio) 3.0 = 0.1% (i.e.
1000-1 ratio) and on and on.

If you work in % numbers just use a set of log tables to the power of two to
find the density numbers.

A 1.7 log density for a four colour image using a good paper printed off-set
lithography would be considered about average.

A good coated art paper or if you like a glossy photographic image would
give a density of around 2.0 give or take a point which, |I might add, is
about the highest density you are likely to achieve.