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Author Chequered pattern appears after scanning
Julian

2005-12-25, 6:14 pm

My photos come out at 150 dpi after scanning (Agfa ScanWise scanner).
The original images show clear colors (taken off a calendar of
Mykonos); however, when viewed in Photoshop the blues (e.g. of the sea)
and all other parts of the image show a sort of chequered or 'moiré'
pattern on the monitor. I can get rid of this with a gaussian blur but
of course this has the effect of unsharpening the images.

Is this a flaw in my scanner, something I am missing in the scanning
process, or is this an unavoidable nuisance?

What is the best way of getting rid of it in photoshop without too much
blurring of the whole image?

Any and all ideas welcome
Lorem Ipsum

2005-12-25, 6:14 pm

"Julian" <woodsjf@sympatico.ca> wrote in message
news:251220051146109145%woodsjf@sympatico.ca...
> My photos come out at 150 dpi after scanning (Agfa ScanWise scanner).
> The original images show clear colors (taken off a calendar of
> Mykonos); however, when viewed in Photoshop the blues (e.g. of the sea)
> and all other parts of the image show a sort of chequered or 'moiré'
> pattern on the monitor.


The Moire effect might be exaggerated when viewing other than 100%. Work at
100%.

> Is this a flaw in my scanner, something I am missing in the scanning
> process, or is this an unavoidable nuisance?


It is almost inevitable due to the way scanning works against a dot-pattern
image.

> What is the best way of getting rid of it in photoshop without too much
> blurring of the whole image?


Filter/ noise / despeckle might help.


Mike Russell

2005-12-25, 6:15 pm

"Julian" <woodsjf@sympatico.ca> wrote in message
news:251220051146109145%woodsjf@sympatico.ca...
> My photos come out at 150 dpi after scanning (Agfa ScanWise scanner).
> The original images show clear colors (taken off a calendar of
> Mykonos); however, when viewed in Photoshop the blues (e.g. of the sea)
> and all other parts of the image show a sort of chequered or 'moiré'
> pattern on the monitor. I can get rid of this with a gaussian blur but
> of course this has the effect of unsharpening the images.
>
> Is this a flaw in my scanner, something I am missing in the scanning
> process, or is this an unavoidable nuisance?
>
> What is the best way of getting rid of it in photoshop without too much
> blurring of the whole image?


This is a moiré patter that often results from scanning printed material.
There are a variety of ways to deal with this - you have already discovered
one of them yourself. Often the scanner software has an option named
"Descreen" or something similar, and I would recommend that you try that.
--
Mike Russell
www.curvemeister.com


Lorem Ipsum

2005-12-25, 6:15 pm

"Mike Russell" <RE-MOVEmike@Curvemeister.comRE-MOVE> wrote in message
news:qEBrf.37367$dO2.13849@newssvr29.news.prodigy.net...

> This is a moiré patter that often results from scanning printed material.
> There are a variety of ways to deal with this - you have already
> discovered one of them yourself. Often the scanner software has an option
> named "Descreen" or something similar, and I would recommend that you try
> that.


Mike, I just thought of something to defeat moiré - making two exposures at
different angles and then merging them. Nonsense? (I would try it myself but
am not at work today.)


Ken Hall

2005-12-25, 6:15 pm

On Sun, 25 Dec 2005 11:46:10 -0500, Julian <woodsjf@sympatico.ca>
wrote:

>My photos come out at 150 dpi after scanning (Agfa ScanWise scanner).
>The original images show clear colors (taken off a calendar of
>Mykonos); however, when viewed in Photoshop the blues (e.g. of the sea)
>and all other parts of the image show a sort of chequered or 'moiré'
>pattern on the monitor. I can get rid of this with a gaussian blur but
>of course this has the effect of unsharpening the images.
>
>Is this a flaw in my scanner, something I am missing in the scanning
>process, or is this an unavoidable nuisance?
>
>What is the best way of getting rid of it in photoshop without too much
>blurring of the whole image?


http://www.scantips.com/basics06.html -- read at least 2 pages
http://graphicssoft.about.com/cs/ph...removemoire.htm
http://home.att.net/~cthames/DeScreen1.htm
http://www.oberonplace.com/dtp/moire/

Ken
Mike Russell

2005-12-25, 6:15 pm

"Lorem Ipsum" <nospam@nospam.com> wrote in message
news:11qtrm6b02k068@news.supernews.com...
> "Mike Russell" <RE-MOVEmike@Curvemeister.comRE-MOVE> wrote in message
> news:qEBrf.37367$dO2.13849@newssvr29.news.prodigy.net...
>
>
> Mike, I just thought of something to defeat moiré - making two exposures
> at different angles and then merging them. Nonsense? (I would try it
> myself but am not at work today.)


I think this is a good idea that could be very effective. In some cases,
particularly black and white material, you can minimize moiré by rotating
the material before scanning.
--

Mike Russell
www.curvemeister.com


Trace Elliot

2005-12-25, 6:15 pm

Ken Hall wrote:
> On Sun, 25 Dec 2005 11:46:10 -0500, Julian <woodsjf@sympatico.ca>
> wrote:
>
>
>
>
> http://www.scantips.com/basics06.html -- read at least 2 pages
> http://graphicssoft.about.com/cs/ph...removemoire.htm
> http://home.att.net/~cthames/DeScreen1.htm
> http://www.oberonplace.com/dtp/moire/
>
> Ken


Or this one:
http://av.adobe.com/russellbrown/GoAwaySM.mov
Gene Palmiter

2005-12-26, 6:19 pm

After the built-in descreening on many scanners the easiest method is to
tilt the original on the scanner. Each original has its own best angle so
experimentation is necessary. Try 15 degrees first. Change your file to Lab
and blur the a and be channels.

--
Thanks,
Gene Palmiter
(visit my photo gallery at http://palmiter.dotphoto.com)
freebridge design group

"Mike Russell" <RE-MOVEmike@Curvemeister.comRE-MOVE> wrote in message
news:qEBrf.37367$dO2.13849@newssvr29.news.prodigy.net...
> "Julian" <woodsjf@sympatico.ca> wrote in message
> news:251220051146109145%woodsjf@sympatico.ca...
>
> This is a moiré patter that often results from scanning printed material.
> There are a variety of ways to deal with this - you have already
> discovered one of them yourself. Often the scanner software has an option
> named "Descreen" or something similar, and I would recommend that you try
> that.
> --
> Mike Russell
> www.curvemeister.com
>
>



Julian

2005-12-26, 6:19 pm

In article <f28d6$43af2097$3e3be867$6771@news.versatel.nl>, Trace
Elliot <trace@elliot.com> wrote:

> http://av.adobe.com/russellbrown/GoAwaySM.mov


Thanks to all of you for all the helpful ideas. A host of great lessons
there.
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