Film scanning file sizes and resolutions

C

Curly

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Hi,

My dad has finally got around to buying a decent enough slide scanner to digitise his 10 thousand slides <- long job.
He got an Epson V700 flat bed.
He read somewhere that he should scan at 3600dpi, but when he does, each image TIFF is like.. 1 GB..
At 2400dpi the tiffs are 450MB, even at 800dpi they are 40MB which seems pretty big.
hes barely computer literate by the way..
I suggested to him; he might want to keep a small ish jpeg and a TIFF for each image. jpeg for general viewing and sharing and the tiff for projecting or printing. Really he wants to chuck his slides once hes scanned them all so needs to find a decent method and stick with it.

Having played around we can barely tell the difference between a 4MB jpeg and a 450MB tiff. It seems to come down to the quality of the slide, and when zooming in the image gets blury way before the pixels are visible. perhaps on sharper more recent slides this might be different but even so.. the jpeg from an 800dpi scan zoomed in could almost fill the wall before you could distinguish it from a high dpi tiff.

Does he really need to be forking out for umpteen 1 terabyte hard drives to save massive files? Or can he make do with small jpegs? Does he really need to scan at large resolutions? Or will 800dpi do?
any advice from *** with more experience would be great, including your own prefered methods :)
thanks in advance! -sorry for long post
Chris
 
What size slides is he scanning? I scan 6x6 at 1800dpi and it produces tiffs at about 25MB.

One thing might be what size they are being output at, I set mine to output at the original size but when I buggered about I was getting 100MB images which was ridiculous.
 
For some reason well beyond me tiff files tend to be massive compared to jpeg's, but if you ever intend processing them anytime in the future I would sggest you save them as tiff files. Have you not considered burning them to CD as you can pick these up for next to nothing at Netto, Aldi & the likes.

Cheers Paul
 
It's all about whether you or he intends to process them afterwards. If yes, then I'd recommend scanning 35mm film at around 1800dpi in a TIFF and 120 film at around 1200dpi. If you're not going to process them but want to keep as a digital archive then you can save them as Jpegs. Of course, the resolution you scan the slides at will also depend on how large you intend printing them.

There is a lot more info on scanning and printing on this site: http://www.scantips.com/

...though it's some pretty intense stuff!
 
Thanks for the replys

Kev M said:
One thing might be what size they are being output at
Click to expand...

This is probably it then, i suggested around 25mb tiffs would be good to keep for future editing or use. Il have to have another look at the scan software see if there is an option, though apparently the included software isnt great.. Is there any way of.. compressing? tiffs in photoshop or some other software?
i get confused about the differences between tiffs and jpegs. i thought tiffs were uncompressed data similar to RAW. But then how can a 800dpi scan produce a 40 MB tiff and then a 1700dpi produce a 25 MB on yours(kevM)? >.<

Thanks for the help anyhoo. Il check that site out :)

Chris
 
There are several compression options available for TIFF. You don't want to treat your image like a FAX document: you want the the LZW type. A six megapixel image will be halved in size to about 17MB (TIFF). Scanning at 2400dpi will give about an 8MP image and I think the compressed TIFFs would be about 23MB.
 
As far as I know the only problem comes if you save in jpeg and then want to process them later you will (or could) end up with pixel grouping/ artefacts

Cheers Paul
 
Be carefull of using LZW compression on tiffs. Some software can't open them. Saving as TIFF is one of the better ways of saving a file, but can eat up hard drive space.

An alternative is to save them as a low compression jpeg ( Photoshop 10 or better) but only open these files. If you want to work on them, save them under a different name. It's the constant opening and re saving the jpeg file is where you start to build up errors. You don't have that probelm with TIFF as it is not compressed.

I'd also agree that for most people a 25-30Mb uncompressed file is usually big enough. Keep the orriginals safe though you never know when you might need them again
 
LZW compression needn't be a problem: IrfanView and other free software will open them and re-save as uncompressed TIFF if required. The uncompressed files could also be ZIP or RAR compressed or saved as PNG, DNG etc. The main thing is to use lossless compression for the archived material, though low compression JPEGs can be very good (large expanses of even colour e.g. blue sky can be their failing).
 
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