Film scanners and dust removal?

Discussion in 'Scanners' started by m II, Dec 23, 2003.

  1. m II

    m II Guest

    How does a scanner determine if an object on the film is actually a
    dust/scratch artefact instead of detail? How common is loss of detail
    because of a confused clean up process?

    I'd like to try making a backlit negative holder for my flatbed
    Scanmaker E6, but I don't know how well it turn out. Once near the top
    of the heap, this thing may well be a dinosaur now. SCSI interface and all.




    mike
    --
    __ __ __ __ __ __ __ __
    / /\ / /\ / /\ / /\ / /\ / /\ / /\ / /
    / /\ \/ /\ \/ /\ \/ /
    /_/ \/_/ \/_/ \/_/ \/_/ \/_/ \/_/ \/_/

    ..let the cat out to reply..
     
    m II, Dec 23, 2003
    #1
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  2. m II

    Tony Spadaro Guest

    Dust is on the film not part of the film. IR dust removal does not remove
    any detail and only in the strongest settings does it slightly soften the
    image
    I have a Scanmaker X6 el which is the larger version of yours . It is
    never going to worth squat for scanning film.
    For about 400 dollars you could get a Canoscan 9900F. This is what I use
    for "contact" scans as it will do four strips of up to six frames at a time.
    However, the quality is nothing like that of a good film scanner. Good
    enough for cataloging etc but I would never do a final film scan with it. It
    has replaced the Scanmaker for reflective material though.
     
    Tony Spadaro, Dec 23, 2003
    #2
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  3. m II

    Bruce Graham Guest

    Just to add to Tony's post. The dust is opaque to the Infrared lamp, but
    the colour film dyes are transparent (ignoring Kodachrome for now), so
    the IR pass provides a map for correction - it shows dust only.

    Does not work for silver B&W (chromagenic OK).

    Does not work for Kodachrome on mine but I think Nikon now claim success
    on their newest scanners.
     
    Bruce Graham, Dec 23, 2003
    #3
  4. m II

    Bandicoot Guest

    You can download a free PS plugin from the Polaroid website for dust and
    scratch removal. Obviously it isn't as good as a system using the IR
    approach, but it does a surprsingly good job. Useful if need to use it for
    an occasional scan from a flatbed, or if you had a film scanner without the
    IR technology.



    Peter
     
    Bandicoot, Dec 23, 2003
    #4
  5. If the scanner uses Digital ICE, it scans four channels, not just
    three: the fourth is in the near infrared. Since dyes in almost all
    color films are quite transparent in near IR, the software can
    separate dust and scratches (opaque in IR) from image (transparent in
    IR). This is why the process doesn't work with traditional
    silver-based black and white, but will work with C-41 dye-based B&W
    films.
    Well, unless it can scan IR as a fourth channel registered with the
    rest, and you can get Digital ICE software, there's not much chance to
    compete with modern film scanners.
     
    Stephen H. Westin, Dec 23, 2003
    #5
  6. Don't know if your scanned is supported but...
    I use "Silverfast" scanner drivers and the only time it doesn't do a good
    job is night shots where the pinpoints of lights look like holes in the
    emulision.
    http://www/silverfast.com
    Doug
     
    Techno Aussie, Dec 23, 2003
    #6
  7. m II

    Ron Andrews Guest

    I will say at the start that I don't have all of the technical answers.
    I routinely use Digital Ice with Kodachrome film and find that it works
    fairly well. The manual for me Minolta Dimage scanner suggests turning off
    the Digital Ice scratch reduction feature for Kodachrome. ASF (now part of
    Kodak) says that Digital Ice will work with Kodachrome but may cause some
    loss of detail especially in images with little red (in other words, lots of
    cyan dye).
    http://www.asf.com/support/Scanners/FilmICEFAQs.shtml#Q8

    If you compare the cyan dye in Kodachrome:
    http://www.kodak.com/global/en/professional/support/techPubs/e55/f002_0492ac.gif
    to the cyan dye in Ektachrome film:
    http://www.kodak.com/global/en/professional/support/techPubs/e55/f002_0492ac.gif
    it looks like Ektachrome might have more IR density, but this is a risky
    assumption since Kodak only displays spectrophotometry up to 700 nm.
    Here are two questions I'd like to answer:

    How much IR density is there in Kodachrome and Ektachrome (or Fuji)
    films?
    Does the Digital Ice problem with Kodachrome have anything to do with
    the relief image?
     
    Ron Andrews, Dec 23, 2003
    #7
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