Which dpi?

Discussion in 'Scanners' started by HC, Sep 5, 2005.

  1. HC

    HC Guest


    Now that I've got my Canon scanner operational again, I've been having
    some discussion regarding dpi and wondering what people here suggest?

    The main group of photos in this project are 3.5 inch x 5.5 inch with a
    few around 6 x 8 inch but all are around 50 year old B&W prints that
    have been stored in albums so their condition is good.

    I've always been under the impression that a higher dpi will give better
    quality prints? I've scanned some photos at 1200dpi at 6 x 8
    inches.....what does everyone suggest for best results?

    Currently I'm saving these as .bmp because .jpg is too lossy and thought
    I'd change this via IrfanView or Picasa. Suggestions on this too
    please? In the past I've just scanned a few photos, but this project is
    archiving old and precious photos so I'd like the best reproduction

    Once these have been scanned I'll burn them to DVD and it seems more and
    more photos are coming out of the woodwork so I'm expecting this will be
    an ongoing archival project.

    Lastly......any suggestions where I might find an audio file to add to
    the DVD? Motor racing/speedway soundtrack would be perfect! Couldn't
    find anything by googling, possibly because I wasn't searching for the
    correct name.

    Thanks in advance for any suggestions
    Bronwyn ;-)
    HC, Sep 5, 2005
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  2. HC

    Ian Riches Guest

    In general, scanning at a higher dpi will give better results - albeit
    at the expense of longer scanning times and larger files. It's a trade-
    off which depends on how much time and storage you have - and what use
    you want to make of the resulting files.

    If you only envisage making same-as-original size prints, then scanning
    at 300dpi will prove fine, IMHO.

    However, if you wish to enlarge the prints, then scanning at a higher
    resolution may well prove beneficial. A *lot*, however, depends on the
    quality of the prints that you are scanning: they may not contain more
    than 300dpi worth of detail. If they were taken on poor camera equipent,
    with poor technique, or have sufferred due to the ravages of time, then
    1200dpi may be wasted on them.

    For best results, I suggest scanning a couple of representative prints
    at 300dpi, 600dpi and 1200dpi, and then "using" each resultant scan in
    the way that you envisage, be that an on-screen display, same-size print
    or enlargement. Can you see any difference? Is the larger file size of
    the higher-dpi files worth any visible difference? Is the difference
    not obvious, but the added "security" of those extra pixels affordable
    in terms of time and storage?
    The "best possible" for your hardware is obviously 1200dpi ;-) Whether
    or not it is worth it is another question altogether.

    You may also wish to look at .tif file formats rather than .bmp for
    archiving. There are non-lossy compression alogotithms available which
    may help reduce file sizes for storage.
    If it is for archive...then I strongly suggest burning more than one DVD
    and storing them in separate places. Then test each DVD periodically to
    check it for deterioration. The long-term reliablity of recordable DVDs
    is far from proven, IMHO.
    No idea. Sorry.

    Ian Riches, Sep 5, 2005
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  3. HC

    catfish Guest

    assuming hard drive space is not an issue.....
    scan as either 1200 or 600 dpi and save as COLOR TIFF files. TIFF are
    more likely to be compatible in future years than bmp files.

    You can "sepia tone" TIFF images if you wish, or you can do a MUCH
    better job of making "grey" for the in between colors by separating
    color layers in paintshop or photoshop or photoshop elements, and then
    adjusting saturation.

    Yes, I know you said BW photos - but the "grey" isn't really "pure
    grey" in these prints any more - the paper has faded and yellowed,
    etc, etc, even though you may not notice it. And at some point, you
    will be asked to do (or will find some) color prints.....may as well
    get accustomed to color scanning now.
    catfish, Sep 5, 2005
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