Best resolution to scan 35mm photographs?

Discussion in 'Archived Threads 2001-2004' started by Rob Gillespie, Jan 13, 2002.

  1. Rob Gillespie

    Rob Gillespie Producer

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    I have a lot of 5x8" prints from photographs taken on various trips. I'd really like to scan all of them and keep them archived on my PC. Ideally, I would like to be able print any of them on a full A4 page (my Epson 890 can print without borders) and keep the quality tip-top.

    The big question - what's the best resolution to scan them at? I've tried 300dpi and they look fine (on the screen), but I'm wondering if it's worth using the extra HD space by scanning them higher. The Twain software that accompanies my Canon scanner allows me to scan up to 3600dpi though I doubt the hardware can really do that. Going from 300 to 600dpi makes for a much larger file - so is it really worth it?
     
  2. Cees Alons

    Cees Alons Moderator
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    Rob,

    If you still have access to the negatives, that would be the way to go. You also need a negatives scanner, like the HP Photosmart Photoscanner (can do prints, dias and negatives). The difference is: negatives contain much more colour information than on the print, so you have more room for adjustments.

    If that's impossible, I think 3600 dpi on positive prints is almost too high, because it is at the grain level of the paper, or even higher already. However, it will allow you to mask some faults by applying Gaussian blur.

    BTW, is that 3600 dpi real (physical) or is it virtual (software interpolated)? In the last case: don't bother.

    I suppose your Canon cannot do negatives (light has to go through)?

    Cees
     
  3. Rob Gillespie

    Rob Gillespie Producer

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    Cees, the scanner is about 3-4 years old now and certainly cannot do anything like a 3600dpi scan - and anyway, the disk space needed to store 400+ photos like that would be prohibitive.

    My Fuji digital camera has a top resolution of 1600x1200 and those look really nice when printed on full A4. File size for those JPEG images is around 700-800kb. I get a similar file size when scanning a print at 300dpi. If I take it up to 400dpi then it's over 1300kb. 600dpi brings the file in at nearly 2mb.
     
  4. Steve_Ch

    Steve_Ch Supporting Actor

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    Negative scanner is the way to go, they do tend to be extpensive (and if you use anything bigger than 35mm, it gets REAL expensive [​IMG] ). There are scanners that come with or you can buy negative and/or transparency adapters, but I tend not to recommend those, as the quality are generally poor. The main reason is because calibration of the light source for negative/transparency is very different than the normal paper media, just putting an adapter over it does not really do the job.
     
  5. Rob Gillespie

    Rob Gillespie Producer

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    A neg scanner is not an option at the moment.
     
  6. John_Bonner

    John_Bonner Supporting Actor

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    Try this site Scantips
    Everything (and more) you wanted to know about scanning.
    The author suggests 300dpi if your intention is mainly to reprint.
     
  7. Rob Gillespie

    Rob Gillespie Producer

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    That's a very useful site - thanks John.
     
  8. Cees Alons

    Cees Alons Moderator
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    Rob,

    A 5x8" CAN be done on a 300 dpi scanner, and if you do some image processing (especially a bit gamma adjustment and unsharp masking) you can get EXCELLENT results on glossy paper. I did this for a co-worker, some weeks ago. She lost the school photograph of her son, the photographer couldn't supply her with another one, and on my advice, she lend a print from a classmate of the boy. The print was 5x8".

    I was able to give her a beautiful A4-size picture! Epson Photo printer, glossy photo paper.

    Now, honestly, I did see a few minor flaws, but she didn't. So the answer to your question is: yes you can do it. The size you really need is about 2200x1500 pixels. That ought to be enough, as far as the spatial resolution is concerned.

    And you hardly lose any colour information that's in the positive print.

    Cees
     
  9. Rob Gillespie

    Rob Gillespie Producer

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    I think I'll play it safe and go for 400dpi from the scanner. That brings the dimensions to a little higher than those you recommend Cees, but the file size isn't THAT much bigger than at 300dpi.

    Thanks for the advice.
     
  10. Keith Plucker

    Keith Plucker Screenwriter

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    You may also want to consider not saving your scans in JPEG format. Try TIFF instead (with LZW compression if your software supports it).

    JPEG is a lossy compression method, TIFF is lossless. Of course, TIFF files will be much larger but they also won't have any JPEG artifacts. I guess it boils down to how many images you have and how much you are willing to spend on disc space.

    -Keith
     
  11. Darren Lewis

    Darren Lewis Supporting Actor

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    Rob, I subscribe to the UK magazine "Digital Photo" which had an article about scanning in a few months ago. Will try to find it (might have lent the issue to my father though). Their cover CD of hi-res images are at 300dpi.

    Can you get a transparancy adaptor for your scanner? We have one for our HP scanner at work and it's pretty good.
     
  12. John Thomas

    John Thomas Cinematographer

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    Rob, have you given thought to a negative scanner?
    [​IMG]
     

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