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This is Interesting: Free Magazines for Graphics designers and webmasters
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 05-25-04 - 12:14 AM 
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"Nikko" <nothanks@yourmomma.com> wrote in message
news:Sjqsc.7377$Tn6.3862@newsread1.news.pas.earthlink.net...
> I just scanned the same picture twice. Once with Descreen off but the
> Unsharp Mask on, the second with Descreen on and no Unsharp Mask (won't
let
> me pick both at the same time- I assume that's standard?). The file with
> Descreen on is 1.25 MB, while the one with it off is 2.5 MB. Any reason
for
> the discrepancy? I'm just wondering why the first file is so small. Am I
> losing information and, as a result, picture quality?
>
> Is there a general consensus on the effectiveness of Descreen? Is there a
> better way to fix the moiré (or whatever it's called - sorry, I'm a
novice)
> using other software? I have both Photoshop 6.0 and Elements 2.0, should
> either of those help. Or is it better to make the adjustment with the
> scanner itself?
>
> Any advice you can pass along to this newbie would be much appreciated.
> Thanks!
>
>
Descreen is for use in scanning half-tone photos, for example from a
newspaper. If you are seeing a Moire pattern, try using the Moire removal
function in an editing program, like Paint Shop Pro. You are much better
off with doing such functions in editing software, than while making the
scan.
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05-25-04 - 12:14 AM
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>I just scanned the same picture twice. Once with Descreen off but the
>Unsharp Mask on, the second with Descreen on and no Unsharp Mask (won't
>let
>me pick both at the same time- I assume that's standard?)
Yes, that is standard.
Descreen is used to scan an image that has been screened, which means printe
d
with a pattern of dots. A printing press is not capable of printing any shad
es
of color or gray; shades of color or gray are "faked" using a "halftone
screen," which is a pattern of dots spaced close together. (Look at a newspa
per
with a magnifying glass and you'll see.)
Anything printed on a printing press--including posters, newspapers, magazin
es,
brochures, and anything like that--should be scanned with "descreen" on.
Otherwise, you end up with a pattern of dots rather than a picture. Anything
that is truly photographic, like a photographic print or a negative, should
be
scanned with descreen off.
Unsharp mask makes a picture sharper. if you turn on unsharp masking with a
screened image, the pattern of dots is sharper and more exaggerated--exactly
the opposite of what descreening does.
>The file with
>Descreen on is 1.25 MB, while the one with it off is 2.5 MB.
How did you save the file?
The size of the file depends on the resolution and size of the scan. Descree
n
on or off will not affect this in the slightest. However, if by "size of fil
e"
you mean "I saved a JPEG," then there might be a difference in the size of t
he
JPEG, because a JPEG file is compressed, and the amount of compression depen
ds
partly on how many hard edges are in the image.
But JPEG compression degrades the quality of the image, and JPEG is only use
ful
where file size on disk is important and image quality is not. So of course
you
would not save a scan you just made as a JPEG, right? Not unless it absolute
ly
had to be a JPEG and no other format would work--for example, for the Web.
>Is there a general consensus on the effectiveness of Descreen?
Most scanner's descreen function works well. It depends on how good the
scanner's software is.
> Is there a
>better way to fix the moiré (or whatever it's called - sorry, I'm a novice)
>using other software?
If the morie is being caused by the halftone screen, the best way to fix it
is
with the descreen function--the scanner will remove the moire as the image i
s
being scanned, while it's still in its most raw state. Descreening after the
scanner is done makes for a picture whose quality is not as good, because th
e
scanner has more information to work with.
--
Biohazard? Radiation hazard? SO last-century.
Nanohazard T-shirts now available! http://www.villaintees.com
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
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05-25-04 - 04:14 AM
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"Tacit" <tacitr@aol.com> wrote in message
> The size of the file depends on the resolution and size of the scan.
Descreen
> on or off will not affect this in the slightest. However, if by "size of
file"
> you mean "I saved a JPEG," then there might be a difference in the size of
the
> JPEG, because a JPEG file is compressed, and the amount of compression
depends
> partly on how many hard edges are in the image.
>
> But JPEG compression degrades the quality of the image, and JPEG is only
useful
> where file size on disk is important and image quality is not. So of
course you
> would not save a scan you just made as a JPEG, right>
Ok, what file format would you suggest? TIFF?
>
novice)
>
> If the morie is being caused by the halftone screen, the best way to fix
it is
> with the descreen function--the scanner will remove the moire as the image
is
> being scanned, while it's still in its most raw state.
I don't know exactly how the original images were made (i.e. halftone or
not). They are black and white photographic prints made in around 1974.
Does that in itself reveal anything about how the prints might have been
made? At any rate, the moiré I saw wasn't nearly as bad as something that's
scanned from a magazine or newspaper. So would you suggest still using the
descreen or is it better treated with software after the fact? Or does that
not change your answer at all?
Thanks again for all you help.
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05-25-04 - 04:14 AM
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>Ok, what file format would you suggest? TIFF?
TIFF and Photoshop (.psd) are both good formats for saving work, yes.
>I don't know exactly how the original images were made (i.e. halftone or
>not). They are black and white photographic prints made in around 1974.
>Does that in itself reveal anything about how the prints might have been
>made?
Look at the picture with a magnifying glass. Is it made up of a bunch of tin
y,
evenly-spaced dots? If so, use the descreening.
>At any rate, the moiré I saw wasn't nearly as bad as something that's
>scanned from a magazine or newspaper. So would you suggest still using
>the
>descreen or is it better treated with software after the fact? Or does
>that
>not change your answer at all?
Depends. If the moire is coming from a halftone screen, then use the
descreening filter; if the moire is a "content moire" (that is, an artifact
of
what the picture is OF--for example, a picture of a fine mesh or screen will
often show a moire), then you may not be able to use the scanner's descreeni
ng
function, and may have to remove the moire in another program.
--
Biohazard? Radiation hazard? SO last-century.
Nanohazard T-shirts now available! http://www.villaintees.com
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
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