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Topic: Resizing Tif Scans ? (Read 248 times)
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Scottiedog
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Posts: 193
Great Uncle George (RNCVR WWI)
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I thought someone else would have responded to this question better than I can, so I left well alone - I see that's not the case, so I'll have a go anyway - be gentle with me.
The brief, one word answer, is yes - you'll lose much of the extra detail you gained by scanning at such a high resolution. The fact that you can't see the difference when you print is simply because your printer can't do justice to the high resolution you originally scanned at.
If space is a problem, you would be far better off using some form of compression technique on the tiff or switching to a compressed file format - or even questioning why you need to scan at 1200 dpi. Remember that there are lossless compression techniques available - jpeg is "lossy".
Les
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Scott (Dublin, Merseyside)
Booth,Houlden,Jarvis,Kenyon,Paver,Wigglesworth (Yorkshire)
Attwater,Crawshaw,Houlden,Lord,Lowe (Lancashire)
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Scottiedog
RootsChat Member
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Posts: 193
Great Uncle George (RNCVR WWI)
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Ahh - you're scanning papers. Are they in colour? You could save considerable space if they're not by switching to greyscale.
You're quite right about jpeg - it's NOT lossless - but with many programs you can control the aggressiveness of the compression and reduce the loss if that's a concern - but I can see why you want to avoid any loss with, say, photos which you might want to edit at a later date. Not so sure about papers though. Perhaps you could have look at what the British Library do.
When considering longterm storage (for posterity) there's much more to worry about than compression losses. How long are you thinking about? Will cd drives be around in 100 years? How long will a cd stay readable for anyway? Even if the cd is readable will the file format be decipherable? - and that's even if the file system can still be accessed - the questions just go on and on.
Unless someone maintains the digital images, converting them and transferring them to new media as time goes by, non-digital storage techniques (i.e. archive quality paper) are probably your best bet, better even than micro-fiche or film.
2000 year old papyrus scrolls can still be read. 100 year old nitrate films self combust! When did you last see a punched card reader? Your grandad's old photos (printed on paper) are still great to look at but how many people have a 35mm slide projector these days?
Am I a luddite? - possibly, but I'm also an IT professional and a realist.
To try to answer your question about what resolution to scan at - let me ask - what do want to do with the images? Edit them, crop them, zoom in to some to fine detail or just print them at their original size? If the latter, 300 dpi is usually considered adequate. I think your own printing experiments may have demonstrated just that.
Sorry about the long post!
Les
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Scott (Dublin, Merseyside)
Booth,Houlden,Jarvis,Kenyon,Paver,Wigglesworth (Yorkshire)
Attwater,Crawshaw,Houlden,Lord,Lowe (Lancashire)
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jmp
RootsChat Senior
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Posts: 434
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Thanks very much for that Les
I understand exactly what you mean about the likelihood of storage and mediums which will become defunct probably fairly quickly, but I would like to do as much as possible to hold on to these items and if necessary to upgrade in due course. I suppose it is a question of hoping for the best to some extent that what I scan at and at what compression etc it is turns out to be compatible at some later stage.
Thanks for the ideas re archive paper etc, that I had not thought of, and will persue that as well
Many thanks again 
Jackie
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Guy Etchells
RootsChat Veteran
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First consideration what optical resolution can be obtained from your scanner?
It may not be capable of an optical scan of 1200dpi and only achieves it by interpolation.
Cheers
Guy
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Scottiedog
RootsChat Member
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Posts: 193
Great Uncle George (RNCVR WWI)
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Yes, that's a good point, Guy.
I just wanted to add that if you decide to use archive paper, you'll also need to look at using special inks too.
Les
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Scott (Dublin, Merseyside)
Booth,Houlden,Jarvis,Kenyon,Paver,Wigglesworth (Yorkshire)
Attwater,Crawshaw,Houlden,Lord,Lowe (Lancashire)
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May I ask what resolution you would scan at to achieve the best results for photos and text