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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.
-----Original Message-----
From: Glen Warner [mailto:gdwarner -at- ricochet -dot- net]
On my most recent project, all of my scroll bars had that annoying
moire effect. I complained to my supervisor, but he said there was
nothing that could be done, but I suspect otherwise.
Any ideas? This manual is to be printed in black and white (or 256
shades of gray). They looked fine on the screen, but when printed ...
:o\
