Digital BW, The Print

The PS gradient does not band.  I believe you are looking at a less than
optimal monitor and/or calibration.  Your crt should not be that bad; you
are setting the white point of the monitor with it’s controls, and
calibrating to native white point, yes?

I assume you are working with the 16-bit generated gradient, not the jpeg.
View at 800% and select a small area of the gradient where you see banding
(gradient reversals), and do an “auto levels” on the selection.  You should
see that the gradient steps are not banded.  You can also set the info
palette to show 16-bit values, and “go-by-the-numbers” to see that there are
no reversals.

I would convert to 8-bit before printing with QTR.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of gp295
Sent: Wednesday, December 13, 2006 6:36 PM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: [Digital BW] Re: New linearization test image uploaded

--- In DigitalBlackandWhiteThePrint@yahoogroups.com
<mailto:DigitalBlackandWhiteThePrint%40yahoogroups.com> , "robert49brake"
<robert49brake@...> wrote:
>
>
> I'd also be interested in hearing from others whether or not
> the banding might just be inherent in the gradient structure of PS.

Robert.

I think you may have nailed down the problem in your post. I went
back and looked at the targets more critically on-screen, and when i
zoomed to Actual Pixels i could see the banding quite clearly.
(Pretty much as clearly as i could see it in my prints.)

Although it was less obvious, unlike you i thought i could see some
banding in the linear ramp when it was also viewed at 100%. Thinking
it might be less obvious simply because my linear ramp was narrower,
i quickly made a full-page linear ramp, and on this image the banding
was as clear as it was on the circular ones.

So it does seem as if the banding problem is something inherent in
the way PS creates gradients. And in my view it occurs in both Radial
and Linear Gradients. I'm surprised i never noticed this before, but
i guess i just never inspected PS gradients on-screen at that
magnification until now.

In fact, when i zoomed to 500%, i realised that the banding also
occurs at a smaller scale as well, though this is not really obvious
to the naked eye because the steps are only about half a millimeter
wide.

Like you, i'd be interested to know if other people confirm what we
think. I'd also be interested to know what people feel about the
usefulness (or otherwise) of my test images, given this (fairly
significant) drawback. If the test-files encourage people to see
problems where there aren't any, it would probably be best to remove
them from the site. (Who's going to remember this explanation in five
year's time?)

Thanks for passing on the explanation, Robert. For the record, i'm
using a calibrated LaCie Electron Blue IV CRT monitor.

Best.

graham



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