What resolution should I be scanning my color prints at?

Discussion in 'Computers' started by Don Black, Jul 8, 2005.

  1. Don Black

    Don Black Screenwriter

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    I'm beginning the process of converting all of my old photo prints to archive-quality digital images. However, I'm unclear as to what resolution I should be scanning them at. My scanner supports up to 2,400 x 4,800 dpi resolution w/ 48-bit color.

    However, I've read that photo prints are only worth scanning up to a certain dpi. Anything above that dpi will capture more data but no added resolution -- e.g., it's pointless to scan at such a high resolution.

    But the numbers I've seen range from 300dpi to 2,400 dpi as what I should use for color prints. Can anyone chime in with their opinion please?

    Thanks!
     
  2. Richard Beckman

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    To capture for an archive I would consider the highest resolution possible and then back up archive (verify backup). Then even as output resolution improves with new displays (i.e. high definition), printers, and faster networks you will always be able to work at the highest fidelity level.

    Now, when the time comes to view or print a specific image set, it only makes sense to derive an output at/above the capabilities of your current need/setup.
     
  3. Rob Gillespie

    Rob Gillespie Producer

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    Scan at the resolution your scanner will support without interpolating. IE if the scanner's highest res is 2400dpi use that rather than interpolated 4800 etc. It all counts, especially if you need to print big. Store the scan in an uncompressed format such as TIFF or maybe BMP. Do all you editing work on a copy of that file so you always have a pristine and unmolested version available.

    That said, if you're scanning a large-ish document, say an 8x10 or A4 then you'll find the resulting file to be massive and possibly unmanageable unless you have a very fast system with a large amount of RAM (i.e. 1gb+). I always scan 35mm negs at 2400 but for say an 8x10 photo I'll drop it to 600. If you do scan at a lower res, use a multiple of the highest available resolution, so for a 2400dpi scanner that would be 1200, 600, 300.

    48-bit images are only supported Adobe Photoshop and Picture Window Pro (maybe one or two others too). Most of the cheaper options (Paint Shop Pro etc) will downconvert to 24bit. 48bit will give you more accurary and is less prone to image degredation, but whether you'll actually notice the difference is open to argument.
     
  4. DaveF

    DaveF Moderator
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    If you're talking about normal photographs, they are your archive images. Those prints should outlast and be better quality than any digital scan. (Photographs last 20 - 100+ years. Harddrives last 5-10 years.)

    Store them appropriately and within a firesafe, and you're archived. If you're really paranoid, make duplicate prints from the original negatives and store those offsite.

    If the scans are a backup against e.g. a fire, then you will need to store the digital media offsite.
     
  5. Ari

    Ari Stunt Coordinator

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    If at all possible, scan the negative instead of the print. For archiving, save it as a TIF as much as possible.
     
  6. Jeff Jacobson

    Jeff Jacobson Cinematographer

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    What makes TIFF the best format to save in? What makes it better than another lossless format?
     
  7. Ari

    Ari Stunt Coordinator

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    The reason why I recommend saving in TIF (aside from being lossless) is that it's the most popular format around (most number of compatible image editing/viewing programs). Years down the road, when programs change and new formats are developed, you are most likely to be able to open TIF files.

    Simple as that.
     
  8. Rob Gillespie

    Rob Gillespie Producer

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    TIFF is independent of operating system. If you save in BMP it's Windows specific. TIFF will open in anything and it also has the advantage of being able to save EXIF data from digital cameras.
     
  9. Scott L

    Scott L Producer

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    What about PNG?

    I also hear lotsa buzz surrounding JPEG2000, any takes on those formats guys?
     
  10. DaveF

    DaveF Moderator
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    Not necessarily. Scanning the negative brings you closer to the original film source. However, because the negative is smaller than a print, you need a scanner with higher resolution to get the same effective sampling density as you can from the print.

    Roughly speaking, you would need 1800 dpi scan resolution for a 35mm negative to equal the results of scanning a 4"x6" print at 600 dpi.

    You also need to make sure your software has appropriate color correction to properly invert the negative to get true color.

    Finally, if this is meant to be true backup, you may want (or need) to calibrate your scanner so your colors are true to the original prints.

    Maybe these are common features and so no worries; I'm not up-to-date on scanner and software features.

    But I'll reiterate: Scan for fun and profit. Scan for medium-term backups and extra safety. But treat your original prints as the true archive and they will outlast any digital version you create.
     
  11. Patrick_S

    Patrick_S Producer

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    When you guys are scanning negatives are you using a special scanner?Well that's not entirely true. Certainly people should always treat their original prints properly (same with the negatives) but a digital backup can last a lifetime. All you have to do is periodically transfer the archive to another drive or other storage medium.
     
  12. D. Scott MacDonald

    D. Scott MacDonald Supporting Actor

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    A couple of comments from somebody who has done this extensively:

    1) I fail to see the value in overscanning a print if your not getting any new information out of it. As far as I can tell, you do not get additional information scanning a print above 360 dpi (you only get bigger files).

    2) If you can scan a negative, on the other hand, 4000+ dpi is great. I use a Nikon Supercool Scan 5000 that works very well for these types of scans. You can pull a LOT more information out of a negative (or slide) than you can a print.

    3) I like archiving my scans in the PNG format, simply because it is a well support, popular format and the resulting files are about a third the size of a TIFF.

    4) All prints and slides will fade/color shift over time (the speed at which this occurs depends on the film or paper used). Digital scans will not fade over time.

    4) The flip side to #4 above (as DaveF points out), is that if you simply store your scans on a single hard drive, you will surely lose them eventually. Furthermore, many naively think that burning them on a CD or DVD is also permanent storage, but the lifetime of the media we burn are much shorter than we think. Also, RAID arrays don't work as well as many think for a couple of reasons that I won't get into. I archive my digital stuff by storing them on multiple computers (not on different hard drives within the same computer) as well as backing up to DVDs. Whatever you do here, you must be very careful or you will lose it.
     
  13. DaveF

    DaveF Moderator
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    Playing with computers for most of my life, I've lost a lot of personal material over the years as I changed storage media, operating systems, and software, and computer designs.

    It's easier now that the Windows-based PC is so entrenched. But I have greater confidence that that my photographic prints will be decent in 30 years than I will be able to load my current digital photos (if they even exist).

    Sidetracking for a moment: I think there is going to be a tremendous loss of personal photographs over the next 20-30 years. Inkjet prints will fade. People will fail to backup their digital images, losing them to CD or DVD failure and hard-drive crashes. Pictures will be lost when people fail (or are unable) to move data to a new system during a major computer transition or technological paradigm shift. But the old prints in the shoeboxes will still look pretty good. [​IMG]

    Sorry to sidetrack; I am interested in effective ways to preserve old and new photos, print and digital.

    And my concern is now the reverse: now that my photography is digital, how do I ensure my pictures will last the rest of my life?
     
  14. Don Black

    Don Black Screenwriter

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    Thanks guys. I think I might start with 600dpi just to be "safe". The Vuescan software only supports JPEG and TIFF formats. However, I'd like to use PNG as my archive format due to space issues. Will I experience any loss in quality converting from TIFF to PNG?
     
  15. D. Scott MacDonald

    D. Scott MacDonald Supporting Actor

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    It is my understanding that digital prints from a professional outfit should still last pretty well.

    I have been scanning a lot of material, some of which dates back 150 years. The prints in general have held up alright. They have gotten dirty, were badly faded, and have color shifter some, but it hasn't been too hard to make them look OK using photoshop.

    Negatives get scratched really easily and also collect dust, but I was able to scan these pretty well for the most part (the oldest negatives I scanned were about 60 years old). If they are well protected they should be OK - if not, they will be useless soon enough.

    Slides, on the other hand, are a mixed bag. I scanned about 2500 slides from different sources and film types. They colorshift and fade very badly, and many of the slides got very dirty. I would not plan on preserving my memories in slide form. While some slides still look pretty good after 50 years, many slides were completely ruined after only twenty years.

    All of this being said, the biggest issue that I had with all of the material that I inherited was that much of it was unidentifiable. People throw their prints in a box without labeling them, and while the print may last 150 years, it's not very interesting without some identification. Also, it was all completely unorganized. While digital scans require diligence to ensure that we don't lose the data (I'm hoping that some technology comes a long that makes long-term archival more reliable), it does have the added benefit that it's much easier to organize and label.
     
  16. DaveF

    DaveF Moderator
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    Scott, thanks for the good tips and insights. I chatted with a coworker, who previously worked for Color Science, and also got a good primer on color theory and printer calibration.

    True, but it's a shame that so many people are at risk of losing valuable photos in the long-run. Fortunately, there have been recent efforts in developing archival ink and paper combinations.

    But looking beyond your life, what will be left for your heirs? Can our digital media survive for 150 years for a grandchild to marvel over? (though, I don't know how a modern color print would fare, either).

    Compared to our our grandparents, our letters and pictures are much more ephemeral, potentially leaving a historical gap in the next century.
     
  17. D. Scott MacDonald

    D. Scott MacDonald Supporting Actor

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    I would also be interested in hearing what a professional says about this.

    But you bring up some really good points. A printed picture will fade, etc., but unless it gets damaged by water or fire, it should last a long time. Digital scans/pictures can also last indefinitely, but they will require occasional maintenance.

    First, one must take care to archive them in such a way so that they will not get lost. It would not surprise me if new technologies are developed to help out in this area.

    Second, if some ancestor found your DVD in 150 years (and the DVD still worked), I find it unlikely that it would be recognized by whatever hardware/OS they are running. This is especially true if you use another program to append new data to a jpg in a nonstandard way. As technology changes, your digital material will need to be reformatted and appropriately re-packaged to change with it (fortunately this should largely be an automated process).

    Another big benefit that I forgot to mention to converting it all to digital, however, is that it makes it much more available - both to yourself and to others that want it. How often will you go through that box of pictures to find pictures of your great grandmother? When it's digital it is always readily available, and you can easily share it with others. Our family tradition is to show a slide show during our family Christmas party. Now it's particularly easy since we simply throw in a CD full of JPGs into our DVD player and let it run.
     
  18. Rob Gillespie

    Rob Gillespie Producer

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    There's been a lot of discussion on this in the past and I'm not sure there was ever a definitive word on it.

    I think realistically, unless you're a real tight-ass with storage, scanning at the scanner's highest native resolution is the best thing you can do (notwithstanding my earlier comment about unmanageable files).
     
  19. Don Black

    Don Black Screenwriter

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    Well, I'm not anal about storage but the files do become unmanageable at the numbers I'm looking at. I can deal with a 20-25MB file but when it becomes 100-150MB, then that's just too freakin' big! Even for my terabyte system. [​IMG]
     

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