How to fix a scanner's resolution??

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Tonto Yoder

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How to fix a scanner's resolution??
« on: 7 Feb 2004, 12:23 pm »
My scanner seems to be losing resolution--it used to be able to scan currency that would almost pass inspection at the local 7-eleven (if the clerk didn't notice it was only one-sided) but now scanning magazine articles yields copies that are readable but not crystal clear.  

Is there any maintenance that would correct this?? It's almost like something's out of alignment.  I assume it's not cost-effective to have a technician work on it: probably better to buy a new one rather than sink $$ into something old???

nathanm

How to fix a scanner's resolution??
« Reply #1 on: 11 Feb 2004, 03:16 am »
Got any examples?

Tonto Yoder

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How to fix a scanner's resolution??
« Reply #2 on: 11 Feb 2004, 11:36 am »
Examples of currency scans no longer available. Otherwise, I've noticed the scanner problem with sharing magazine articles etc. online--
http://home.comcast.net/~brighter/linn4.pdf

These used to come out better.

bubba966

Re: How to fix a scanner's resolution??
« Reply #3 on: 11 Feb 2004, 11:38 am »
Quote from: Tonto Yoder
Is there any maintenance that would correct this??


http://www.audiocircle.com/index.php?topic=8140

nathanm

How to fix a scanner's resolution??
« Reply #4 on: 11 Feb 2004, 08:24 pm »
If the jaggy pixels in the PDF is the problem you're referring to then that's not entirely the original image, it's the settings used to distill the PDF, of which there are a fair amount.  Also, images in PDFs never look quite right on screen because of the goofy interpolation, so that's also a factor.

The original image from your PDF is 498x863 pixels which in and of itself is borderline okay given the text size, however the JPEG compression is severe and JPEG compression on small text is always a mess.  So either the original image was saved with too much compression or Acrobat Distiller was resampling the image with too much compression.  An uncompressed scan at that size would be legible, but add in the other stuff and it starts falling apart.

On top of all this is the matter of descreening a halftone image from a magazine.  Very few low end scanners do a decent job with this and it's always tricky finding the right setting.

So there's a number of factors working against this Linn page scan which probably does not mean your scanner is malfunctioning outright.  It is most likely just a matter of using the wrong settings.

Tonto Yoder

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How to fix a scanner's resolution??
« Reply #5 on: 11 Feb 2004, 11:16 pm »
Thanks,
while much of what you said was Greek to me, I did try using Black & white Bitmap setting and tweaked the threshold(?) to end up with a readable text.  This'll never work for sharing porn though. :D

nathanm

How to fix a scanner's resolution??
« Reply #6 on: 12 Feb 2004, 03:26 am »
Try scanning the magazine at these settings:

RGB color
100%
200ppi

optional: descreen: 133 or 150 lpi (if it exists)

See if you get any moires (weird patterns of dots throughout the image) then.  Go down in resolution as long as the text is staying legible.

Also, there's no real need to save them as PDFs.  JPEG would make more sense considering you're just dealing with a bitmap image.  Then your recepients could just view them in a browser and not have to muck with Acrobat.  Save them with a "High" quality compression level and see what you get when you reopen it.