manual file types

From: der Mouse <mouse_at_Rodents.Montreal.QC.CA>
Date: Tue Feb 1 11:16:28 2005

> I was once fooled by the following logic: 'well it was printed in
> bilevel, so there's no sense in going above that'. What's wrong
> there is that there's need for subpixel information [...]

Also, the argument - quite aside from the subpixel issues - assumes
that the page being scanned is exactly equal to the page as it was
printed. This is rarely the case, and many of the common types of
difference will show up on a scan (creases and smudges being perhaps
the commonest).

> I choose 300dpi grayscale but if I had to-had to use bilevel I'd go
> above 600dpi possibly all the way to 1200. There's even ways to
> transform that back to 300dpi grayscale if need be,

But such a reconversion can't recover much of the lost information, not
unless a bilevel scan actually dithers. This doesn't matter if you
want multilevel just for subpixel reasons, but it does if, for example,
there is a smudge that scans as black on a bilevel scan but isn't as
black as the text.

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Received on Tue Feb 01 2005 - 11:16:28 GMT

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