> [David Paschal]
> > On the other hand, for 1-bit depths (lineart, halftone), 0 means
> > white and 1 means black. Is there any particular reason for this,
> > especially since xsane and xscanimage both end up having to invert
> > it anyway in order to display a preview?
> This sounds like a bug to me. The only partly sensible reason I can
> make up on the fly to use a encoding like this is to make sure black
> writing on white paper give mostly 0 bits.
That's not a bug, it's the PBM image format, see pbm(5):
# It was originally designed to make it reasonable to mail
# bitmaps between different types of machines using the typical stupid
# network mailers we have today.
[...]
# - Width * height bits, each either '1' or '0', starting at the top-left
# corner of the bitmap, proceeding in normal English reading order.
#
# - The character '1' means black, '0' means white.
And yes, it obviously was designed that way, so a human can see the
image without using a graphics display program, just by looking at
the ASCII representation (assuming a large screen and proper formatting,
the manpage has a tiny example).
Regards,
Ingo
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This archive was generated by hypermail 2b29 : Mon Sep 11 2000 - 00:32:35 PDT