RE: print-prep (was: Adobe Photoshop Justification)

Subject: RE: print-prep (was: Adobe Photoshop Justification)
From: Max Wyss <prodok -at- prodok -dot- ch>
To: Emru Townsend <etownsen -at- Softimage -dot- com>
Date: Fri, 6 Oct 2000 00:13:33 +0200

Emru,

thanks for the flowers. Indeed, the solution you show is quite
universally usable. Instead of bothering with any pattern which could
create a moiré (well, sometimes is that much in a field that one does
not even think about that someone else does not know a term <g>),
just get rid of the pattern and replace it with a grey level.

It is absolutely a solution. However, it may not be automatizable in
such a way that it would work for a bigger number of images. On the
other hand, I am not quite sure if there isn't a or a group of
Photoshp filters which would take care of such patterns. There are
some scanner software which does actually get rid of screens (which
is not that far different from patterns).



Max Wyss
PRODOK Engineering
Low Paper workflows, Smart documents, PDF forms
CH-8906 Bonstetten, Switzerland

Fax: +41 1 700 20 37
e-mail: mailto:prodok -at- prodok -dot- ch
http://www.prodok.ch



[ Building Bridges for Information ]


______________________






The closest thing to a good solution was Max Wyss's suggestion, but it's far
from universal. What's interesting to note is that no one has bothered to
explain what a moire (spelt with an acute accent on the e, pronounced as its
French origin implies: mwah-ray) is:

When the clash of two screens
Makes your print not look keen
That's a moire.

And there lies your solution. For those who don't know what a screen is,
it's the means by which shades of grey are printed using only black ink.
The screen creates a halftone pattern, which are those little dots of
varying sizes (either white dots on black or black dots on white) that
simulate grey tones. The principle is very similar to dithering on a
computer screen, except that with halftones you can vary the size of the
dots.

The moire comes into effect when the halftone which comes from printing the
image on paper clashes with the dithered colors in your scroll bar. What
dither, you ask? I'll show you: grab a screen shot with a scroll bar in it,
then zoom in on the scroll bar with your favorite image editor/viewer.
You'll see that the scroll bar is made up of alternating white and grey
dots.

So: eliminate the dither and you eliminate the moire.

If you're using Photoshop, here's one way of doing it. It's more work the
first time, but after that it's zip zip zippy.

(1) Select the eyedropper tool. In the Eyedropper Options palette, change
the sample size to a 3 by 3 or 5 by 5 average.
(2) Click the Info tab on the same palette.
(3) Select one of the grey dots in the scroll bar. (Make sure it's in the
middle of the dither pattern.) If you look at the Info palette, you'll see
an RGB value while your eyedropper hovers over the pixel. That's the RGB
value of the final grey you'll be using. Write it down.
(4) Use the selection tool to select the dithered area of the scroll bar.
(5) From the main menu, select Edit > Fill (you can also right-click the
selection in Windows, or Option-click on the Mac). Your settings should be
Foreground color, 100% opacity, Normal mode. Click OK. Repeat on the next
section of the scroll bar if necessary.
(6) Save and grin.

Now that you've got the RGB value, you can do this anytime in just a few
seconds, especially if you automate part of the process with an action or
two.




Previous by Author: Re: Acrobat Reader and "post-it" notes
Next by Author: Re: Translations... dogma or realism?
Previous by Thread: RE: print-prep (was: Adobe Photoshop Justification)
Next by Thread: RE: print-prep (was: Adobe Photoshop Justification)


What this post helpful? Share it with friends and colleagues:


Sponsored Ads