Non correlated noise - speckles in scanned photographic images

I've been trying to scan some old black and white photos
( that I was trying to digitally archive) using a HP scanjet
4500c at 300dpi (256 greyscale). Recently, I
noticed random white speckles/dots in places where
the scanned image should be a uniform dark or black.
The original non-glossy photo was old but clean and
it did not have not any smudges or stains so I thought
maybe it was just a dirty scanner - so I cleaned
the exterior surface of the flatbed scanner glass and
careful cleaned the interior surface of the glass
surface. However, even after the cleaning the scanned
images still had a significant amount of white speckles
in them. So l researched the topic on the hp.com
website. I appears - this type of random scanning
error is called non-correlated noise and it is attributed
to how light refracts off non-glossy photographic
paper; HP.com suggests that one can reduce this type
of error by rotating the original source 90 degrees when
scanning. I noticed that rotating the original photo did
reduce the scanning noise but it did not eliminate
it - the white speckled scanning errors just appeared
elsewhere in the image. So I tried another scanner,
HP 2200c, but I got similar results. So far I haven't
found much information on the internet about
how to get rid of this type of scanning error...does
anyone have a solution to this problem short of
fixing the problem in photoshop?

"drydem" wrote in message
ups.com...
I've been trying to scan some old black and white photos
( that I was trying to digitally archive) using a HP scanjet
4500c at 300dpi (256 greyscale). Recently, I
noticed random white speckles/dots in places where
the scanned image should be a uniform dark or black.
The original non-glossy photo was old but clean and
it did not have not any smudges or stains so I thought
maybe it was just a dirty scanner - so I cleaned
the exterior surface of the flatbed scanner glass and
careful cleaned the interior surface of the glass
surface. However, even after the cleaning the scanned
images still had a significant amount of white speckles
in them. So l researched the topic on the hp.com
website. I appears - this type of random scanning
error is called non-correlated noise and it is attributed
to how light refracts off non-glossy photographic
paper; HP.com suggests that one can reduce this type
of error by rotating the original source 90 degrees when
scanning. I noticed that rotating the original photo did
reduce the scanning noise but it did not eliminate
it - the white speckled scanning errors just appeared
elsewhere in the image. So I tried another scanner,
HP 2200c, but I got similar results. So far I haven't
found much information on the internet about
how to get rid of this type of scanning error...does
anyone have a solution to this problem short of
fixing the problem in photoshop?



I have not seen the white speckles/dots on any photos that I have scanned on
my Canon 8400F.

You might try the descreen function and see what happens.
If you are scanning a photograph that is on textured paper, Descreening may
help.
The textured pattern would appear as a halftone screen to the scanner.

If the scanner does not have a descreen function in the driver, you can try
scanning at a much higher resolution, try 1200 DPI. You can reduce the file
in a photo editor afterward if that takes care of the speckles/dots.

Moire
http://www.scantips.com/basics06.html

Manual methods for descreening:
http://www.scantips.com/basics6c.html

--
CSM1
http://www.carlmcmillan.com
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In article . com,
says...
I've been trying to scan some old black and white photos
( that I was trying to digitally archive) using a HP scanjet
4500c at 300dpi (256 greyscale). Recently, I
noticed random white speckles/dots in places where
the scanned image should be a uniform dark or black.

Make a scan.
Move the pic to different place on the scanner.
Make another scan.
Are the speckles in the same place?

If so, look at surface of print with loupe, and you'll find your
speckles.

MM

On Nov 3, 8:51 pm, MoiMoi wrote:
In article . com,
says...

I've been trying to scan some old black and white photos
( that I was trying to digitally archive) using a HP scanjet
4500c at 300dpi (256 greyscale). Recently, I
noticed random white speckles/dots in places where
the scanned image should be a uniform dark or black.

Make a scan.
Move the pic to different place on the scanner.
Make another scan.
Are the speckles in the same place?

no.


If so, look at surface of print with loupe, and you'll find your
speckles.

MM

I used photo editor zoom function to find the random speckles.