With the caveat that I don't know the technology behind Digital Ice when used with a flatbed scanner, here is and explanation for why it fails on real B&W negatives on film scanners. By "real B&W" I mean gelatin silver negatives and not the chromogenic ones of recent years.
The trick used by Digital Ice on film scanners to get rid of dust and scratches on the film is that an additional IR sensor is used to create a second image during the scan.
This second image in limited to the IR spectrum. That means that for practical purposes, the original image is completely transparent for this scan.
If everything is clean and scratch free, this IR scanned image will be completely clear.
If there is dust on the film, then the dust particles will most likely be opaque to the IR scan and show black on the IR image.
Digital Ice compares the IR image to the 'regular' image and everywhere they are the same ( dust is opaque in a normal scan ) it assumes that the spot detected
is caused by dust or a scratch on the film. It then switches to recovery mode, and, using surrounding pixels, recreates the missing information.
I have a slide that has a blob of some black and tarry stuff on it from the processor. Digital Ice found it and completely removed it from the image so that you can hardly tell it was there. Fortunately, in this case, the area obscured by the 1/8 inch diameter blob on a 35mm frame was in the sky so the job was easier.
All that aside, when you turn on Digital Ice on a real silver negative, guess what, the silver grains are opaque to the IR scan. Digital Ice gets an image of each grain or grain clump as if it were dust. Back to the plain scan where that scan images all those nice little grains as black on white. Digital Ice 'fixes' everything up and you get and extremely low contrast image with 90 or so percent of the image missing and 'corrected' for.
Anyway, that's what happens in a Nikon film scanner and may also happen in a flat bed.
Anyone out there do a B&W scan on their flatbed with Digital Ice turned on? It would be nice to know whether the same technology is use there also.
Cheers,
James
PS: this information came as a result of hours of tech support calls to the original company before it was purchased by Kodak some time back. I ended up talking to one of their design engineers and we worked out why my brand new ( at that time ) Nikon 4000 dpi scanner gave such c____y results. Tuned Digital Ice off for all B&W scanning and did my own dust / scratch control in PhotoShop.
At 03:24 PM 1/7/2009 -0500, you wrote:
We, my husband and I, have a new V750 Epson Perfection Pro Scanner and want to scan 35mm and 4 X 5 black and white negatives. It came with Silverfast Ai. I have heard that VueScan is easier? better?. I also think digital ice does not really work well on b&w negatives.
My fear is that I have a mix of information and misinformation. Can folks on this list recommend resources for mastering b&w negative scanning? We will use the scans for digital printing and for digital negatives for Pt/Pd printing in the darkroom. We can learn from online information or books or even a workshop if there is such an animal.
This is list is such a wealth of information that I am sure you will have some resources to get us started down the right path.
Thanks in advance,
Rene
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Rene Hales
See my photos.
http://www.pbase.com/halesr/galleries
