Scanned images have whorls

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desertryder

I'm using an Epson 4490 to scan some 4 x 5 black and white negatives.
Scans are 1200 DPI, 16 bit greyscale, using no sharpening, minimal
grain reduction, minimal dirt reduction and file format is TIFF (large,
non-lossy format for printing photos). Most scans are fine but now and
then I'll get a scan that has areas of whorls in the image. It appears
to be random but if I rescan it'll show up in the same place. I've
tried scanning at different DPIs, different file formats, scanning to
24 bit color, etc., but no change. I've tried using Epson's Digital Ice
on the scans (great for removing defects, dirt, etc.) but it doesn't
seem to help the whorls.

Image example can be viewed at:
http://home.earthlink.net/~toalice/picture_test.htm
I've reduced the image size and converted to JPEG (original scan size
was 48 MB!) and included a detail blowup.

I've noticed it on some other scans of 2.25 x 2.25 and 35 mm negatives
also. Is this just a film to digital anomaly or is has anybody else had
this happen using the Epson 4490? Also, any suggestions on avoiding
this? TIA.
 
I'm using an Epson 4490 to scan some 4 x 5 black and white negatives.
Scans are 1200 DPI, 16 bit greyscale, using no sharpening, minimal
grain reduction, minimal dirt reduction and file format is TIFF (large,
non-lossy format for printing photos). Most scans are fine but now and
then I'll get a scan that has areas of whorls in the image. It appears
to be random but if I rescan it'll show up in the same place. I've
tried scanning at different DPIs, different file formats, scanning to
24 bit color, etc., but no change. I've tried using Epson's Digital Ice
on the scans (great for removing defects, dirt, etc.) but it doesn't
seem to help the whorls.

Image example can be viewed at:
http://home.earthlink.net/~toalice/picture_test.htm
I've reduced the image size and converted to JPEG (original scan size
was 48 MB!) and included a detail blowup.

I've noticed it on some other scans of 2.25 x 2.25 and 35 mm negatives
also. Is this just a film to digital anomaly or is has anybody else had
this happen using the Epson 4490? Also, any suggestions on avoiding
this? TIA.
Click to expand...

Hello,

this is most certainly a case of Newton Rings. See:
http://en.wikipedia.org/wiki/Newton's_rings
it arises when the film to glass plate distance varies from place to place in
the order of wavelengths (400 - 700 nm).

How to avoid this is another matter: I suppose others with practical experience
on the subject can help you here. Personally I have never scanned films on
glass. It may be that increasing the distance between film and glass in the
order of 0.1 mm will do the trick, but how to do that in practice is another
matter.

Greetings, Alex
 
Alex said:
Hello,

this is most certainly a case of Newton Rings. See:
http://en.wikipedia.org/wiki/Newton's_rings
it arises when the film to glass plate distance varies from place to place
in
the order of wavelengths (400 - 700 nm).

How to avoid this is another matter: I suppose others with practical
experience
on the subject can help you here. Personally I have never scanned films on
glass. It may be that increasing the distance between film and glass in
the
order of 0.1 mm will do the trick, but how to do that in practice is
another
matter.

Greetings, Alex
Click to expand...

You cut paper strips and put under the edge of the negative, to raise the
negative off of the glass.

Or you use the proper negative holder.
 
Since you are using a 4490 that has a narrow light source in the lid and
thus will have to scan in strips, CSM's idea about the strips may actually
work. Normally, the film would most likely just sag to the glass if you
tried to just lay paper shims around the thin edges of 4x5. Try to get
stock that is 1 mm thick and cut a full mask (including calibration gap) out
of black material with a window as wide as the software will actually allow
you to scan in film scanning mode (around 60 mm). Tape if necessary to
prevent the sagging.

One other thing you might try is to flip the film over to the emulsion/least
glossy side of the film and place that side of the film against the glass.
Some films have enough texture to prevent Newton Rings.

In regard to ICE and black and white film, it will not work with traditional
b/w film. It will work with the newer C41 processed films though.

Doug
 
Or you use the proper negative holder.
Click to expand...

I forgot to post that I am using the Epson holder for 4 x 5 negs. There
is a very slight concavity of the negative while in the holder. Not
much I can do about that as the negatives are quite old, 50 + years.
 
- said:
Since you are using a 4490 that has a narrow light source in the lid and
thus will have to scan in strips, CSM's idea about the strips may actually
work. Normally, the film would most likely just sag to the glass if you
tried to just lay paper shims around the thin edges of 4x5. Try to get
stock that is 1 mm thick and cut a full mask (including calibration gap) out
of black material with a window as wide as the software will actually allow
you to scan in film scanning mode (around 60 mm). Tape if necessary to
prevent the sagging.
Click to expand...

Wouldn't that be the same as the film holder supplied by Epson, which I
am using? (sorry I didn't mention that in original post) or would this
be
One other thing you might try is to flip the film over to the emulsion/least
glossy side of the film and place that side of the film against the glass.
Some films have enough texture to prevent Newton Rings.
Click to expand...

That would, of course, flop the image and I think it would also affect
the focus. I can adjust the flop with PS but how serious would the
focus issue be? I use unsharp mask in PS but hate to overapply it.
 
SNIP
I forgot to post that I am using the Epson holder for 4 x 5 negs.
There is a very slight concavity of the negative while in the
holder.
Click to expand...

You can try reversing the film in the holder, and correct the
orientation in post-processing.

Bart
 
On Friday, July 21, 2006 5:16 AM,
Image example can be viewed at:
http://home.earthlink.net/~toalice/picture_test.htm
Click to expand...

These are Newton's Rings, caused when the film base comes into intimate
contact with the glass. A small proportion of light is reflected from the
glass to the film and back again. Each band represent a difference in the
glass-film distance of one light wavelength, as the reflected light waves
reinforce or subtract from the light waves travelling directly through the
film and glass.

If you are scanning glossy side down, scanning emulsion side down should
cure the problem, because the emulsion side usually has a rougher surface.
You may also get better focus, because the image is not then separated from
the glass by the thickness of the film base. Also you will not get the
light
scattering of diffusion of the image which could occur if the image is
scanned through the film base.

You will need to flip (mirror) the image after scanning.

Peter
 
Peter said:
On Friday, July 21, 2006 5:16 AM,


These are Newton's Rings, caused when the film base comes into intimate
contact with the glass. A small proportion of light is reflected from the
glass to the film and back again. Each band represent a difference in the
glass-film distance of one light wavelength, as the reflected light waves
reinforce or subtract from the light waves travelling directly through the
film and glass.

If you are scanning glossy side down, scanning emulsion side down should
cure the problem, because the emulsion side usually has a rougher surface.
You may also get better focus, because the image is not then separated from
the glass by the thickness of the film base. Also you will not get the
light
scattering of diffusion of the image which could occur if the image is
scanned through the film base.

You will need to flip (mirror) the image after scanning.

Peter
Click to expand...

I will try scanning the images emulsion down and thanks to everyone for
their responses.
 
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