"Chicken skin" effect when scanning b/w images

I have an ancient cheap Acer scanner that works just fine for me the
few times I need it.

The one thing it does miserably though is scanning black and white
photos out of books. I've tried scanning pictures from old high
school yearbooks, or pictures out of books so my kids can use them in
history reports, and here's what happens:

I get an image with a pattern of dots visible all over the darker
portions. It looks like there was a net draped over the image. Or it
looks like the image has goosebumps. I'll call it the "chicken skin
effect" because the evenly-spaced translucent dots look like the
surface of skin from uncooked poultry.

Is there some special technique I'm supposed to be using when scanning
black and white photos (any photos maybe) from books? Mind you, my
scanner's not great, but text comes out fine, color or black and white
standalone photos come out great, it's only when scanning from a book
that I get this phenomenon.

Yes, as best I can, I press down on the scanner cover while the scan
is occurring. I've even left the cover up and pressed down on the
book hard enough that the page is clearly hard up against the glass.

This one is driving me nuts. Anyone else ever see it? And what's the
answer?

Contact the person or business that holds the copyright to the image and
purchase reproduction rights from them.

KB




"jersie0" wrote in message
...
I have an ancient cheap Acer scanner that works just fine for me the
few times I need it.

The one thing it does miserably though is scanning black and white
photos out of books. I've tried scanning pictures from old high
school yearbooks, or pictures out of books so my kids can use them in
history reports, and here's what happens:

I get an image with a pattern of dots visible all over the darker
portions. It looks like there was a net draped over the image. Or it
looks like the image has goosebumps. I'll call it the "chicken skin
effect" because the evenly-spaced translucent dots look like the
surface of skin from uncooked poultry.

Is there some special technique I'm supposed to be using when scanning
black and white photos (any photos maybe) from books? Mind you, my
scanner's not great, but text comes out fine, color or black and white
standalone photos come out great, it's only when scanning from a book
that I get this phenomenon.

Yes, as best I can, I press down on the scanner cover while the scan
is occurring. I've even left the cover up and pressed down on the
book hard enough that the page is clearly hard up against the glass.

This one is driving me nuts. Anyone else ever see it? And what's the
answer?

jersie0 wrote:
I have an ancient cheap Acer scanner that works just fine for me the
few times I need it.

The one thing it does miserably though is scanning black and white
photos out of books. I've tried scanning pictures from old high
school yearbooks, or pictures out of books so my kids can use them in
history reports, and here's what happens:

I get an image with a pattern of dots visible all over the darker
portions. It looks like there was a net draped over the image. Or it
looks like the image has goosebumps. I'll call it the "chicken skin
effect" because the evenly-spaced translucent dots look like the
surface of skin from uncooked poultry.

Is there some special technique I'm supposed to be using when scanning
black and white photos (any photos maybe) from books? Mind you, my
scanner's not great, but text comes out fine, color or black and white
standalone photos come out great, it's only when scanning from a book
that I get this phenomenon.

Yes, as best I can, I press down on the scanner cover while the scan
is occurring. I've even left the cover up and pressed down on the
book hard enough that the page is clearly hard up against the glass.

This one is driving me nuts. Anyone else ever see it? And what's the
answer?

You'll find some help he
http://www.scantips.com/
Look under "de-screening" or such



--
Frank ess

jersie0 wrote:
I have an ancient cheap Acer scanner that works just fine for me the
few times I need it.

The one thing it does miserably though is scanning black and white
photos out of books. I've tried scanning pictures from old high
school yearbooks, or pictures out of books so my kids can use them in
history reports, and here's what happens:

I get an image with a pattern of dots visible all over the darker
portions. It looks like there was a net draped over the image. Or it
looks like the image has goosebumps. I'll call it the "chicken skin
effect" because the evenly-spaced translucent dots look like the
surface of skin from uncooked poultry.

Is there some special technique I'm supposed to be using when scanning
black and white photos (any photos maybe) from books? Mind you, my
scanner's not great, but text comes out fine, color or black and white
standalone photos come out great, it's only when scanning from a book
that I get this phenomenon.

Yes, as best I can, I press down on the scanner cover while the scan
is occurring. I've even left the cover up and pressed down on the
book hard enough that the page is clearly hard up against the glass.

This one is driving me nuts. Anyone else ever see it? And what's the
answer?

You get the "dotted" scanned image because the original image is dotted.
You are not scanning a continuous tone B/W photo. You are scanning a low
resolution, printed image. It is composed of many fine discrete dots.
Your scanner SHOULD have a setting for scanning images printed from
Newspapers, Magazines, Fine Art Prints, etc.
In your case, you should select the setting for newspapers.
It won't "Cure" the problem but it will help a lot.
Bob Williams

Or to summarise, if the scanner doesn't have a descreen or demoire
function built-in, just:

1. Scan at about twice the resolution you need.
2. Use an image editor or browser to blur the image (experiment to work
out how much)
3. Resample the image down to the size you need. (if the editor has
different resizing algorithms, you may need to experiment again to find
the best result)

The moire pattern should be reduced or eliminated.

wrote:
Or to summarise, if the scanner doesn't have a descreen or demoire
function built-in, just:

1. Scan at about twice the resolution you need.
2. Use an image editor or browser to blur the image (experiment to work
out how much)
3. Resample the image down to the size you need. (if the editor has
different resizing algorithms, you may need to experiment again to find
the best result)

The moire pattern should be reduced or eliminated.

Hi...

I agree... and add that a carefully chosen degree of
edge preserving smooth will help, too.

Ken

Ken Weitzel wrote:


wrote:

Or to summarise, if the scanner doesn't have a descreen or demoire
function built-in, just:

1. Scan at about twice the resolution you need.
2. Use an image editor or browser to blur the image (experiment to work
out how much)
3. Resample the image down to the size you need. (if the editor has
different resizing algorithms, you may need to experiment again to find
the best result)

The moire pattern should be reduced or eliminated.


Hi...

I agree... and add that a carefully chosen degree of
edge preserving smooth will help, too.

Ken


The Median filter can be useful too, but again you may need to sharpen
your edges afterwards.

Cheers
Steve

On Wed, 09 Feb 2005 15:28:02 +1300, Bartshumandad
wrote:



Ken Weitzel wrote:


wrote:

Or to summarise, if the scanner doesn't have a descreen or demoire
function built-in, just:

1. Scan at about twice the resolution you need.
2. Use an image editor or browser to blur the image (experiment to work
out how much)
3. Resample the image down to the size you need. (if the editor has
different resizing algorithms, you may need to experiment again to find
the best result)

The moire pattern should be reduced or eliminated.


Hi...

I agree... and add that a carefully chosen degree of
edge preserving smooth will help, too.

Ken


The Median filter can be useful too, but again you may need to sharpen
your edges afterwards.

Sometimes rotating the original anywhere between 5 & 45 degrees
(experiment) on the scanner bed can help the above filters work
better.

--
Owamanga!

Wanted to thank everyone for the great suggestions. Yeah, the Morais
(spelling?) issue was what I was dealing with, and all the tips here
helped.

jersie0 wrote:
Wanted to thank everyone for the great suggestions. Yeah, the Morais
(spelling?) issue was what I was dealing with, and all the tips here
helped.

mmwah-ray (Dinah Shore syndrome)

moiré