Re: [O] [OT] Scanning for archiving

[Marcelo de Moraes Serpa]

Thanks Achim!

On Sat, Nov 5, 2011 at 2:34 PM, Achim Gratz <address@hidden> wrote:

Marcelo de Moraes Serpa <address@hidden> writes:
> I just bought a scanner and started to scan important documents as a
> backup, and archiving them with meaningful metadata in orgmode files.
> Then a question came to mind - what dpi to use? I'm not really savvy
> when it comes to scanning or printing, and I want like a dpi that
> allows me to reprint the document at an acceptable quality later if
> necessary, but that also doesn't take that much space (600dpi pdfs
> take around 5MB).

Fax in fine mode has about 200dpi resolution.  The raw scan should be in
higher resolution (usually 2x-4x the target resolution depending on the
document quality).  The file to be archived then needs to be compressed
(lossless compression is preferred, e.g. TIFF or PNG) and the bit depth
reduced (black and white, usually).  When making PDF files you need to
make sure that the image data doesn't get re-coded (often into much
inferior JPEG).  For documents containing (color) images it is often
preferrable to separately treat text and images.  The best compression
would be achieved if the whole text was extracted via OCR, but that is
probably a lot more effort than you're willing to spend.


Regards,
Achim.
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