Digital BW, The Print

Barry,

If you create a gradient in PS and then posterize it creating 21 distict
patched you get a histogram with 21 vertical lines. This is because the
image is no longer a gradient.

Now, if you create a second gradient without posterizing it so that it is as
smooth as Photoshop can make it you will have a histogram that is sold with
a gradual arc that is high at the ends and slopes down a bit in the center.

There may be roughness at the top along the curve, but you do not have deep
fingers indicating that data is missing.

Mike


----- Original Message -----
From: "flyfishingusa2002" <tflyfish@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Sunday, March 24, 2002 11:08 AM
Subject: [Digital BW] PhotoShop Histograms leading us astray?


> I have been following all the threads regarding "Combing" and "Step-
> Wedges" with great interest. I have been looking at there Histograms
> in Photoshop and trying to figure out what it was telling me. I have
> been seeing a lot of "stray" information in the Histograms that
> confused me, so I decided to try the following:-
>
> 1  I did a selection of just the wedge part of the published
> standard Step wedge by Jon Cone and MIS
>
> 2  I, via PhotoShop 6, drew a simple rectangle filled with a
> graduation from 0% - 100% grey.
>
> Neither of the above gave me a "Clean" Histogram. I fully expected
> #2 to do so. I see lots of little comb teeth and a variation in the
> histogram height when I thought it should be constant.
>
> Could it be that the "Combing" is something that Photoshop is
> introducing and does not really appear on our finished print?
>
> I have also noticed that on the step wedge that those little white
> dividing lines do not appear between all the steps on some
> magnifications and not on others.
>
> I am no PhotoShop expert, but the above seems a little odd, maybe we
> are all being lead astray by PhotoShop?
>
> Barry
>
>
>
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