Re: Experiences with digitizing material not suitable for aflatbed

From: Andrew Stawowczyk Long (anlong@NLA.GOV.AU)
Date: Wed Apr 05 2000 - 23:38:38 CDT

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    Message-Id: <200004060440.VAA21788@dns.ccit.arizona.edu>
Date:         Thu, 6 Apr 2000 14:38:38 +1000
From: Andrew Stawowczyk Long <mailto:anlong@NLA.GOV.AU>
Subject:      Re: Experiences with digitizing material not suitable for aflatbed
To: mailto:IMAGELIB@LISTSERV.ARIZONA.EDU

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    Mark,

    Here in the National Library of Australia we did couple of projects that involved digitising at high resolution. We aim d at 300dpi at 100%. As we were working with unique, fragile and oversized material
    (rare maps, manuscripts) we couldn't use a flat bed scanner. Instead we worked with high-end digital scanning back comb ned with a Sinar large format camera. It worked extremely well for most items achieving the required resolution. The back was Phase One with 8,400 x 6,000 pixel resolution and 36-bit internal colour depth. Some of the maps we needed to shoot in tiles, later stitching them together on a computer to get 300dpi resolution. It can be avoided by using a new Phase One back called Power FX with resolution exceeding 12,000 x 10,000 pixels.

    Some of the important things to be aware of:

    - Required light levels are very high - can be dangerous from the archival point of view.
    - Power conditioners (stabilisers) have to be used for lights as light levels have to be maintained very acurately durin
     5-20 minutes of exposure.
    - High resolution lenses (designed for digital capture) have to be used.
    - Powerful computers with large hard disks and a lot of RAM (500Mb - 1Gb) are needed.
    - Scanning back and computers need to be colour calibrated to a known standard (we use CIE D65) and colour profiles need to be used (ICC) to maintain colour accuracy throughout the system chain.
    - It is a common practice to capture at 36 or 48-bit colour depth and then reduce it to 24-bit for storage. It gives be t results.

    Also, we evaluated an option for capturing images on film (4" x 5" transparencies) and scanning them later on but the re ults were not satisfactory. It was due partially to the much lower dynamic range of a photographic film than those of digital devices (typically for film it is 6 f-stops and at least 11 f-stops for high q ality digital devices). Also, it is much more labor intensive and more expensive.

    I hope that'll help. Let me know if you need more info.

    Regards

    Andrew Stawowczyk Long Public Affairs Officer National Library of Australia Phone: +61 2 6262 1382 EMAIL: mailto:anlong@nla.gov.au

    >
    > >>> Mark Jordan <mailto:mjordan@SFU.CA> 04/06/00 11:02 >>>
    > Hi,
    >
    > We've been doing some research on the costs of equipment suitable for
    > digitizing material such as books, oversized posters, drawings, etc. that
    > we wouldn't want to (say pages from a rare and fragile book) or couldn't
    > (because of size) scan with a flatbed, even one with a 12x17" platten. To
    > get 24-bit color at a 300 dpi or higher, we'd have to spend quite a bit of
    > money.
    >
    > Does anyone have any experience with alternative methods of digitizing
    > largish-size material not suitable for scanning with flatbeds into 24-bit
    > color, high resolution images? For example, could photograph the items,
    > create high-quality prints or slides, and then scan the photo? Or is this
    > kind of method just not practical?
    >
    > Thanks for sharing any experiences you may have had with this kind of
    > material,
    >
    > Mark
    >
    > Mark Jordan
    > Librarian / Analyst, Systems Division
    > W.A.C. Bennett Library, Simon Fraser University
    > Burnaby, British Columbia, V5A 1S6, Canada
    > Email mailto:mjordan@sfu.ca / Phone (604) 291 5753 / Fax (604) 291 3023

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    <!doctype html public "-//w3c//dtd html 4.0 transitional//en">
    <html> Mark,
    <p>Here in the National Library of Australia we did couple of projects that involved digitising at high resolution.&nbsp; We aimed at 300dpi at 100%.&nbsp; As we were working with unique, fragile and oversized material
    (rare maps, manuscripts) we couldn't use a flat bed scanner.&nbsp; Instead we worked with high-end digital scanning back combined with a Sinar large format camera. It worked extremely well for most items achieving the required resolution. The back was Phase One with 8,400 x 6,000 pixel resolution and 36-bit internal colour depth.&nbsp; Some of the maps we needed to shoot in tiles, later stitching them together on a computer to get 300dpi resolution.&nbsp; It can be avoided by using a new Phase One back called Power FX with resolution exceeding 12,000 x 10,000 pixels.
    <p>Some of the important things to be aware of:
    <p>- Required light levels are very high - can be dangerous from the archival point of view.
    <br>- Power conditioners (stabilisers) have to be used for lights as light levels have to be maintained very acurately during 5-20 minutes of exposure.
    <br>- High resolution lenses (designed for digital capture) have to be used.
    <br>- Powerful computers with large hard disks and a lot of RAM (500Mb
    - 1Gb) are needed.
    <br>- Scanning back and computers need to be colour calibrated to a known standard (we use CIE D65) and colour profiles need to be used (ICC) to maintain colour accuracy throughout the system chain.
    <br>- It is a common practice to capture at 36 or 48-bit colour depth and then reduce it to 24-bit for storage.&nbsp; It gives best results.
    <p>Also, we evaluated an option for capturing images on film (4" x 5" transparencies) and scanning them later on but the results were not satisfactory.&nbsp; It was due partially to the much lower dynamic range of a photographic film than those of digital devices (typically for film it is 6 f-stops and at least 11 f-stops for high quality digital devices). Also, it is much more labor intensive and more expensive.
    <p>I hope that'll help.&nbsp; Let me know if you need more info.
    <p>Regards
    <p>Andrew Stawowczyk Long
    <br>Public Affairs Officer
    <br>National Library of Australia
    <br>Phone: +61 2 6262 1382
    <br>EMAIL: mailto:anlong@nla.gov.au
    <br><a href="http://timeframes.natlib.govt.nz/"></a>&nbsp;
    <blockquote TYPE=CITE>&nbsp;
    <br>>>> Mark Jordan &lt;mailto:mjordan@SFU.CA> 04/06/00 11:02 >>>
    <br>Hi,
    <p>We've been doing some research on the costs of equipment suitable for
    <br>digitizing material such as books, oversized posters, drawings, etc. that
    <br>we wouldn't want to (say pages from a rare and fragile book) or couldn't
    <br>(because of size) scan with a flatbed, even one with a 12x17" platten. To
    <br>get 24-bit color at a 300 dpi or higher, we'd have to spend quite a bit of
    <br>money.
    <p>Does anyone have any experience with alternative methods of digitizing
    <br>largish-size material not suitable for scanning with flatbeds into 24-bit
    <br>color, high resolution images? For example, could photograph the items,
    <br>create high-quality prints or slides, and then scan the photo? Or is this
    <br>kind of method just not practical?
    <p>Thanks for sharing any experiences you may have had with this kind of
    <br>material,
    <p>Mark
    <p>Mark Jordan
    <br>Librarian / Analyst, Systems Division
    <br>W.A.C. Bennett Library, Simon Fraser University
    <br>Burnaby, British Columbia, V5A 1S6, Canada
    <br>Email mailto:mjordan@sfu.ca / Phone (604) 291 5753 / Fax (604) 291 3023</blockquote>
    </html>

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