Scanning Photo Prints: Max Rez?

Discussion in 'Photography' started by (PeteCresswell), Feb 15, 2013.

  1. I am scanning a box of old photographs.

    Scanner defaults to 600 dpi, but will do up to 1200.

    Zooming in on some test scans of a studio-quality portrait in PhotoShop,
    I can see the diff between 300 and 1200.

    But the zoom level needed for pixellation to set in at 300 is high
    enough that 300 seems ok to me - and 1200 takes a looooong time to scan
    whereas 300 goes pretty quickly.

    Am I missing anything? i.e. somewhere further down in the process of
    scanning many photos per pass, cutting-pasting them into separate JPEG
    documents, and saving same am I going to wish that I had scanned at a
    higher rez than 300?
     
    (PeteCresswell), Feb 15, 2013
    #1
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  2. (PeteCresswell)

    Anon Guest

    "(PeteCresswell)" wrote in message

    I am scanning a box of old photographs.

    Scanner defaults to 600 dpi, but will do up to 1200.

    Zooming in on some test scans of a studio-quality portrait in PhotoShop,
    I can see the diff between 300 and 1200.

    But the zoom level needed for pixellation to set in at 300 is high
    enough that 300 seems ok to me - and 1200 takes a looooong time to scan
    whereas 300 goes pretty quickly.

    Am I missing anything? i.e. somewhere further down in the process of
    scanning many photos per pass, cutting-pasting them into separate JPEG
    documents, and saving same am I going to wish that I had scanned at a
    higher rez than 300?
    --
    Pete Cresswell

    Pete,

    I use an older Plustek 7200 film scanner that does a decent job for my
    archiving of old B/W's from the 60's and a bit beyond. I think the time
    used to scan at the highest resolution is worth it since I don't really know
    what I may want to do with these in the future. A poster perhaps or simply
    make some collages to be included for on-screen viewing or to be included
    into a book as some have. Having been thru one flood and losing books full
    of archived prints and film sleeves, I want to insure what is left is
    protected and having them in an electronic format - that while not totally
    future proof, does provide the added insurance I want.

    So while my film scanning differs from your scanning of prints, the end
    result is the same - preservation. I actually spend more time cleaning the
    film before scanning than I do scanning and that cuts down considerably the
    time spent in post production and cleaning things up with PS or LR. Old
    photographs (from what I've learned) should never be subjected to a cleaning
    of the physical print unless done with specific knowledge of the paper and
    emulsions and how to do it properly. I do not and have managed to screw-up
    several that made them virtually useless. Best to leave the original as-is
    and scan and restore the electronic version.

    So your post production restoration work may be the only way to save a print
    and it will most certainly be more time consuming than the amount of time it
    takes to scan a print. The effort is usually worth the time for those
    photographs that show "How we were" and will be enjoyed by future
    generations.

    So yes - you're missing something. Technology aside (i.e., I don't know what
    scanner or software you're using) but scan for "future-use" and preserve
    what you can while you can, using the best technology you feel you can
    afford. Your grandkids and their children will appreciate your efforts in
    saving a part of history for them which cannot be found anyplace else in the
    world.

    And please don't archive them in the jpg format.


    Bob S.
     
    Anon, Feb 15, 2013
    #2
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  3. (PeteCresswell)

    DanP Guest

    If your prints resolution is not better than 300 dpi then 300 dpi is all you need. Your scanner might go up to 1200 but viewed at pixel level it will not be as good as 1200.

    If you scan the photos to view them on a computer a rough size of 3000 pixels by 2000 would be enough. If you want to make bigger prints then is a lot of work to do and I would say use a professional scanner and specialized software.

    1200 dpi is 4 times as big as 300 dpi but that is linear measuring. Area is 16 times bigger and so is file size.


    DanP
     
    DanP, Feb 15, 2013
    #3
  4. Per Anon:

    ..TIFF?

    Photoshop's format?
     
    (PeteCresswell), Feb 15, 2013
    #4
  5. (PeteCresswell)

    Tony Cooper Guest

    Depends. Normally, Photoshop files are saved as a .PSD file. But
    both .TIFF and .PSD retain layers. .TIFF is also an Adobe format,
    ..TIFF is a Lossless format, but .JPG is a Lossy format.

    For a detailed explanation, see
    http://www.cambridgeincolour.com/tutorials/imagetypes.htm
     
    Tony Cooper, Feb 16, 2013
    #5
  6. You don't say how big they are which makes a difference. I would ask myself
    what is the biggest size I might want to print them, and how many ppi I
    would want to print them at. This tells you the size in pixels you need and
    you can work back to see what resolution is needed.

    Suppose they are postcard size (about A6) but you might want to print them
    at A4, at 300ppi. A4 is twice the lenght and width of A6, so you would need
    to scan the originals at 600dpi to get the size you need.

    It's probably worth scanning at a few resolutions to establish the max
    detail so that you don't waste time scanning at a greater resolution than
    is warranted. The detail will depend not just on the print technology used
    but how sharp the camera lens was, often film outresolves the lens and
    scanning at a highest resoltion just records film grain not image detail.

    It's easy to be fooled by grain structure into thinking that the image is
    sharper than it really is. I would do something like, scan a couple at 300,
    600, 1200 then resample the lower res images up to the same size as the
    highest one using the best interpolation routine available (e.g. Lanczos).
    Now give a dose of sharpening to them all and examine them side by side at
    200% magnification and try to find fine image detail (e.g. individual hairs
    on a person's head) that is present in one but not another, this will tell
    you at what point no more detail is being revealed.
     
    Gordon Freeman, Feb 16, 2013
    #6
  7. (PeteCresswell)

    DaveL Guest

    I,too, have delved into archiving old photographes and tried to find out
    the best way to scan for the best possible results. The advice I
    received was to scan at the optical resolution of the scanner, you can't
    get any better result. Most, if not all, scanners can output a range of
    resolutions, both higher and lower, but only work in the one, the
    optical resolution. This would be the fastest scan as the time taken by
    the software to produce a different resolution is avoided.

    Also the advice to save in a lossless format is very important for
    archiving as you or someone else will need to reprocess the image later.
    Convert to jpeg or whatever to distribute them to others is a good idea
    as it reduces the storage size for those who don't need to.

    If your scanner will only produce images in jpeg, I don't know if and
    do, convert them to a lossless format before doing anything else to
    presurve the quality even saving into a converter before saving the file
    if you can.

    Dave L
     
    DaveL, Feb 16, 2013
    #7
  8. (PeteCresswell)

    Alan Browne Guest

    300 dpi is about as much detail as there is on most colour prints.

    B&W prints (really sharp and contrasty) go about 400 or a bit more.

    You can "over sample" (600) and then re-sample in your photo editor as
    needed but that won't expose more detail - it generally just means
    larger files.
     
    Alan Browne, Feb 16, 2013
    #8
  9. (PeteCresswell)

    Alan Browne Guest

    It doesn't matter. He should scan at the "available information"
    resolution (300 dpi will do).
     
    Alan Browne, Feb 16, 2013
    #9
  10. (PeteCresswell)

    Alan Browne Guest

    The optical resolution of most any scanner is far, far better than the
    available information from a print. So one is better off to simply scan
    for the available information. 300 dpi is about right for a colour print.
     
    Alan Browne, Feb 16, 2013
    #10
  11. (PeteCresswell)

    PeterN Guest

    On 2/16/2013 8:42 AM, Alan Browne wrote:

    true. But if correction is needed it is important to have the extra
    information.
     
    PeterN, Feb 16, 2013
    #11
  12. (PeteCresswell)

    Michael Guest


    Pete,

    Photographic papers typically have a surface resolution of 250 DPI.
    So your scanner default rez of 600 is fine.
    But, as others have said here your final product (printing, archiving,
    or web posting) determines what the resolution of the initial scan
    need be.

    A very good webpage on scanning is here;
    <http://www.scantips.com/>

    Michael........
     
    Michael, Feb 16, 2013
    #12
  13. (PeteCresswell)

    John Turco Guest


    To maximize compatibility, I think it would be best to also save the
    scans as JPEG files, even if an archival format is used.

    By the way, your "sig delimiter" doesn't work, here in Mozilla
    "Thunderbird" 17.0.2...hence, maybe, "nospam" was right?

    John
     
    John Turco, Feb 17, 2013
    #13
  14. (PeteCresswell)

    PeterN Guest

    To me the important issue is why nospam made such a fuss about it.
     
    PeterN, Feb 17, 2013
    #14
  15. All very true.

    I know people say scan to the maximum resolution (of the Lens->Film->Photo
    *system* which is limited by the lowest resolution component in theory)
    but... Film grain is often treated as waste yet it is an integral part of
    the image and does play a role in perceived sharpness. So I'm left wondering
    if it's better to scan to the maximum theoretical resolution or capture the
    grain as well. The issue is grain comes in all shapes and sizes and may add
    a quality to the image. Has this been tested? If so what larger resolution
    should be used to capture the photo? Two times? Four times? Larger?
     
    Charles E. Hardwidge, Feb 17, 2013
    #15
  16. (PeteCresswell)

    Savageduck Guest

    Here is a scan @ 600 dpi and resized to 1522x1920.
    < https://dl.dropbox.com/u/1295663/FileChute/Evans-05AACV1920.jpg >
     
    Savageduck, Feb 17, 2013
    #16
  17. (PeteCresswell)

    Nil Guest

    It doesn't work because there's no space character after the dashes. IN
    order for it to work correctly, a sig delimiter needs to be "-- " (dash
    dash space, without the quotes.)
     
    Nil, Feb 17, 2013
    #17
  18. (PeteCresswell)

    DaveL Guest

    This why I was advised to scan at the optical resolution of the scanner.
    You can change the pixal count both up and down but there will be no
    more information available. A lot of scanners can produce images with a
    higher resolution number than the optical resolution but does that
    improve the image?
    Dave L
     
    DaveL, Feb 18, 2013
    #18
  19. I still need to get a scanner sometime and scan some old photos. I only have
    a couple of dozen or so so can afford to scan as high as the scanner goes.

    I wouldn't scan higher than the optical resolution as that's just
    interpolation isn't it? You just end up adding whatever artefacts are in the
    algorithm at the time which seems silly to me.

    If the typical resolution of a print is somewhere between 300-400 lines I'd
    like to scan to capture grain as well. I have no idea how high this would be
    but I don't think 4x or 8x is too much. Then there's always the possibility
    of printing from the scan. I'm thinking that properly capturing grain would
    be helpful here.

    I've seen experts be wrong enough times because they're asking the wrong
    questions so tend to agree with you. Scanning to the maximum available
    (certainly of current consumer resolutions) does sound like a good idea.
     
    Charles E. Hardwidge, Feb 18, 2013
    #19
  20. (PeteCresswell)

    John Turco Guest


    Yeah, that's exactly what "nospam" said!

    John
     
    John Turco, Feb 19, 2013
    #20
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