Scanning resolution for prints

Discussion in 'Film Discussion and Q & A' started by Stillwater, Nov 12, 2008.

  1. Stillwater

    Stillwater TPF Noob!

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    Hello all,

    Recently I've run into some 'quality control' snags with my scanned photos. For showing them online, I've had no problem scanning at 200dpi and resizing to about 500xwhatever (roughly flickr's 'medium' size) and them looking fine/great. But I do portraits, family photos, and what not for friends and I want to give them quality product. If they're going to pay me, I feel they need high quality. Anyways, to the question. What resolution should I scan the photos to make them acceptable for at least an 8x10, or just to make sure they don't look like crap (i.e. grainy) at larger sizes?

    I'm using a hp all-in-one type scanner, which can scan up to some un-godly high number of dpi that I would never consider using as a setting, so there aren't really any limitations there.

    Thanks!
    --George
     
  2. TwoRails

    TwoRails TPF Noob!

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    The general formula is to scan at 300dpi for every inch of enlargement you want. So, for easy math, if you have a 1 inch square to start with, then you'd scan at 3000dpi to get a 10 inch photo, 1500 for a 5", and so on. Some playing around is usually in order as scanning at higher res's you will also pick up the paper itself and other things: for instance, if you scan a photo on matt paper, you'll might be able to see it in the scan. You will also see a poor quality photo enlarged: for example if it's a poor quality 4x6 print, the larger print may look like the Sunday comics under a magnifying glass. Close examination of the original will reveal "it's in there," too...

    HTH

    TwoRails :)
     
  3. Stillwater

    Stillwater TPF Noob!

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    My fears may be coming true. I get my photos developed at walgreens (lack of resources to do it myself), but not a specific one, and I've never put any thought into quality per store. I just figured the machines were tuned to turn out an average photo every time. Any advice if part of the abnormalities are the developing/paper? I won't be fiscally able to buy equipment, but could i scan the negatives on my flatbed and work from there or is that even worth the effort?

    --George
     
  4. MikeBcos

    MikeBcos TPF Noob!

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    Back when I shot film I found that the quality of the prints was down to the skill of the operator, I found the operator who produced the results I liked best and always had my film developed on her shift.

    Scanning your negs is probably your best bet but you do need a scanner with a film attachment, I picked mine up at Goodwill for $15.
     
  5. Stillwater

    Stillwater TPF Noob!

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    Aha! Well then, thrift store hunting I shall go. Thanks for all of the help!
     
  6. TwoRails

    TwoRails TPF Noob!

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    Yes, if you can scan the negs, it's the best way as you're starting with the source. Sadly, negs are not always available for prints I need to scan. As far as what to do if the abnormalities are the developing/paper? you need to do what you can in your image editor. There's no real one answer. Naturally you'll have the typical spot and scratch removal but I've not figured out how to fix poor quality or the like to a quality that looks like it's straight from a negative. Smoothing and or sharpening helps on some, but not others, and often I don't really like the outcome. I just experiment a lot until I reach a point where it is acceptable, considering the source and who (and why) they will be viewing it. The next time I have a need, for giggles I'm thinking about taking a shot of the print and see how that comes out compared to scanning the same print.
     
  7. tonymp

    tonymp TPF Noob!

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    Hi George,
    it's obviously best to scan from the neg rather than scan a print - however sometimes we have no choice as we don't have the original negative. The main problem with scanning prints is the quality of the original print and the all important size! It's usual to scan prints at around 260 -300 dpi to get decent results.

    To scan a neg effectively on a flatbed you'll need a resolution of about 2500 dpi or greater to get decent results.

    I use an Epson 4990 to scan medium format and occasional 35mm negs. It does better with colour negs and medium format but 35mm is pretty decent too.
    Below is a quick & simple example of a scan of a neg (from Fuji Reala + a Canon A1 & humble FD 35-70 ) - the car was an old Opel ( circa 1937) and I took the shot hurriedly in the back streets of the Russian city of Chelyabinsk ( towards Siberia) as they still don't like people wandering round with cameras ( shades of the old Soviet days LOL).
    The image was scanned at 2500 dpi for speed, but it hasn't come out too bad considering.

    If your scanner can can scan at 2500dpi without being interpolated, you should certainly get some good results from neg scans..
    Regards...
    Tony
    [​IMG]
     
  8. Helen B

    Helen B TPF Noob!

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    George,

    Most high street labs use digital printers for printing film these days. They expose light sensitive paper using LEDs or lasers, and they usually have a resolution of 300 ppi. It is, however, usually worth scanning the prints at higher than that if you can. If you simply scan at 300 ppi you will probably end up with a scan that has a lower true resolution that 300 ppi, because any of the scanner's imperfections will have their effect. Unless you pay a lot of money, scanners are generally let down by their optics and mechanics - they don't always deliver what the ppi value promises.

    In this kind of situation it is generally better to oversample, so that the print resolution is maintained as best as possible - I would recommend scanning at a minimum of 600 ppi, preferably 1200 ppi. With careful post processing you should be able to have a sharp-looking, smooth 8x10 from a 4x6, albeit one lacking detail.

    As already mentioned, it is much better to scan the negatives.

    Best,
    Helen
     
  9. Stillwater

    Stillwater TPF Noob!

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    Ok, I tried it, and now I have questions. (Of course! :))
    Scanner setting:2500dpi
    I didn't use any sort of dust remover settings, so that is why there are specs. (and i didn't clean the glass either)
    I imported it as a 16-bit .tiff but had to reduce to 8-bit for Gimp.
    I played with the curves and levels a little bit, and I obviously need more work.
    But, it is still so grainy, I scaled this down about 90%, but I think you all can still see where my problems are.

    [​IMG]

    Why are there still lines/such a grainy texture? I tried to reduce the noise of the picture but it just made it worse I think. I'm currently using Gimp for my editing, but I have access to CS3 on my desktop if I need to use it.

    Thanks for all of your help!
     
  10. frXnz kafka

    frXnz kafka TPF Noob!

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    Is your scanner just a regular flatbed scanner? If so, you aren't going to get usable film scans from it, it just isn't made for it. Your profile says you're a university student, so I would suggest finding out if your school has a scanner made for scanning film. Most of the ones at my school at least have a film attachment, and we have a few dedicated film scanners (Nikon Coolscans).

    If that doesn't work out, I would suggest bringing them to a camera store or something and having them scan the film.
     
  11. Stillwater

    Stillwater TPF Noob!

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    Ah, well that would make sense then wouldn't it? Well then, I suppose I'll ask around and see what I can find! Thanks Derek!
     

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