28 Jan
2005
28 Jan
'05
7:38 a.m.
der Mouse <mouse(a)rodents.montreal.qc.ca> wrote:
You don't need Acrobat, no matter what a bunch of
webpages may claim.
GhostScript groks PDFs just fine.
Indeed, ghostscript comes with a script that eats PDF and produces PS.
The problem is that PS recreated from PDF can never be as good as the
original PS from which the PDF was made. I'm not saying that PDF should
be banned, making a file format illegal would be just as much against
Cosmic Law as making a weed illegal. What infuriates me is that people
have PS and they ASSUME that I want PDF instead, and they convert their
PS to PDF and send me the PDF and not PS. I want the original PS!
MS
28 Jan
28 Jan
7:55 a.m.
From: "Michael Sokolov" <msokolov(a)ivan.harhan.org>
der Mouse <mouse(a)rodents.montreal.qc.ca> wrote:
My original point was to skip PS and go directly from TIFF to PDF. Just as
going from PDF to PS is not as good as going directly to PS going from PS to
PDF adds an extra unnecessary step that creates a less efficient PDF. While
a very few people prefer PS the rest of the world wants PDF's.
I will not post PS docs for the simple reason of $. I pay commercial
servers to post my files and to post PS docs along with PDF's would cost me
more money.
I do not charge anyone for documents but I do pay others to provide them.
Randy
You don't need Acrobat, no matter what a
bunch of webpages may claim.
GhostScript groks PDFs just fine.
Indeed, ghostscript comes with a script that eats PDF and produces PS.
The problem is that PS recreated from PDF can never be as good as the
original PS from which the PDF was made. I'm not saying that PDF should
be banned, making a file format illegal would be just as much against
Cosmic Law as making a weed illegal. What infuriates me is that people
have PS and they ASSUME that I want PDF instead, and they convert their
PS to PDF and send me the PDF and not PS. I want the original PS!
MS 
8:02 a.m.
I will not post PS docs for the simple reason of $. I
pay commercial
servers to post my files and to post PS docs along with PDF's would
cost me more money.
Would you be willing to make the PS, or even the TIFF files, available
to people for them to post? Depending on the space involved, I'd
tentatively be willing to host copies of the TIFFs on my own box.
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8:38 a.m.
From: "der Mouse" <mouse(a)rodents.montreal.qc.ca>
I'd be happy to send you or anyone else copies of what I have, most of the
manuals on my site were scanned by others. I quickly went to the full blown
Acrobat which goes directly from scanner to PDF without saving any
intermediate files.
I'll check and see what I have.
Randy
I will not
post PS docs for the simple reason of $. I pay commercial
servers to post my files and to post PS docs along with PDF's would
cost me more money.
Would you be willing to make the PS, or even the TIFF files, available
to people for them to post? Depending on the space involved, I'd
tentatively be willing to host copies of the TIFFs on my own box.
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse(a)rodents.montreal.qc.ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B 
9:04 a.m.
Michael wrote:
The problem is that PS recreated from PDF can never be
as good as the
original PS from which the PDF was made.
Huh? If you have a PDF containing nothing but G4 fax compressed bilevel
images, and convert it to PS, you get the same G4 images with a different
wrapper. How is that any worse?
9:45 a.m.
On Fri, 2005-01-28 at 15:04 -0800, Eric Smith wrote:
Michael wrote:
of course it's still a bilevel image rather than greyscale, so you mess
up a lot of diagrams and images within the documentation, and go a long
way toward ruining the chances of someone running a useful OCR scan over
the data at some future point :-(
I can't remember exactly what documentation's being discussed; bilevel's
great for documents that are still pretty common but if it's something
rare then it doesn't do much on the preservation front :-(
The problem is that PS recreated from PDF can
never be as good as the
original PS from which the PDF was made.
Huh? If you have a PDF containing nothing but G4 fax compressed bilevel
images, and convert it to PS, you get the same G4 images with a different
wrapper. How is that any worse?
10:20 a.m.
Michael wrote:
The problem is that PS recreated from PDF can never be
as good as the
original PS from which the PDF was made.
I wrote:
Huh? If you have a PDF containing nothing but G4 fax
compressed bilevel
images, and convert it to PS, you get the same G4 images with a
different wrapper. How is that any worse?
Jules wrote:
of course it's still a bilevel image rather than
greyscale, so you mess
up a lot of diagrams and images within the documentation, and go a long
way toward ruining the chances of someone running a useful OCR scan over
the data at some future point :-(
We were comparing the merits of PDF vs. Postscript, and what happens
when you convert between them. The point was that most scanned manuals
are in lossless bilevel form, such as G4. That's a native image format
in both Postscript and PDF, so there should be no loss of data or
usefulness converting in either direction. (If there is, the conversion
program is arguably broken.)
Whether documents should be scanned in greyscale is an entirely
separate discussion. Both PDF and Postscript support the common
lossy and lossless greyscale and color encodings, so there should
not be any loss of data or usefulness converting those in either
direction.
Where converting from PS -> PDF -> PS is a bad idea is when the
original Postscript file contains a lot of complex native Postcript
rendering, in which case the conversion to PDF "flattens" it, and
converting back may yield suboptimal results. For archiving of
scanned documents this would not occur.
I can't remember exactly what documentation's
being discussed; bilevel's
great for documents that are still pretty common but if it's something
rare then it doesn't do much on the preservation front :-(
Lossless bilevel encoding at a high enough resolution (generally at least
300 DPI) is suitable for text and line art, and can still be OCRed just
fine. If the document has very small text or very detailed line art,
higher than 300 DPI resolution may be required. I've seen few documents
with text or line art that wasn't reproduced well with a 400 DPI bilevel
scan.
If the document has continous-tone images such as photographs, lossless
bilevel encoding is usually NOT adequate. For archival purposes, such
images should ideally be saved in a lossless greyscale or color encoding,
though for working documents lossy compression such as JPEG is OK.
If there's one thing I can't stand, it is text and line art compressed
with JPEG. Text and line art have sharp edges, which is high-frequency
information. If you apply JPEG compression, the high frequencies are
discarded, making the text and line art blurry. People who advocate
this usually say something like "but I set the 'quality' to 95%". That
*still* results in blurry text, yet larger file sizes than lossless
bilevel compression.
Eric
7268
days inactive
7268
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6 comments
5 participants
participants (5)
-
eric＠brouhaha.com -
julesrichardsonuk＠yahoo.co.uk -
mouse＠Rodents.Montreal.QC.CA -
msokolov＠ivan.Harhan.ORG -
randy＠s100-manuals.com