Scanning old manuals

From: Eric Smith <>
Date: Tue Mar 9 19:14:32 1999

Stephen Dauphin <> asks:

> Well this brings up the idea whether PDF is the be all and end all format.

I wouldn't bet on it. But it seems to be pretty ubiquitous on "modern"
computers (vs. "classics"). Since I use modern computers for all my
administrative tasks, it doesn't bother me. I know that there are people
who try to use classic computers for everything, and there's nothing wrong
with that, but I'm not going to go very far out of my way to accomodate
it either.

> Isn't PDF format determined by Adobe
> Or is a more public and open group determining the direction?

Yes, AFAIK they have unilateral control over it.

> and don't they keep changing the file spec?

The 1.2 spec is published at:

The 1.0 spec was available in book form, but I don't think they've published
printed editions of newer specs.

They've just announced version 1.3 of the spec in conjunction with their
Acrobat 4.0 product.

The changes have always been upward compatible. From reading the 1.0 and
1.2 specs, it is apparent that any compliant 1.0 PDF file should work
fine with a compliant 1.2 reader. I assume the same relation holds
true for versions 1.1 and 1.3.

> My only experience is with PDF on a Mac.
> Acrobat 1.0 for Mac, which works on 68000 machines, could still read 2.0
> format files and display them, albeit while complaining about errors.
> Acrobat 2.0, which needs a 68020 minimum, shows a variety of errors and
> all it displays is a blank page, on what I presume are PDF files recently
> converted with 3.0.
> So what PDFs are we actually making?

I'm producing PDF version 1.2 files, which probably require version 3.0
or newer of Acrobat Reader.

Version 1.0 of PDF required that all binary images be encoded in hexadecimal
or base 85, so version 1.0 PDF files of scanned images would be rather
than binary PDF files using later versions of the spec. This means that
readers that only understand version 1.0 probably don't work with binary
PDF files.

As far as I know, I am not taking advantage of any PDF features that
are not present in version 1.1 other than "linearization". I believe that
my PDF 1.2 files should work correctly with a reader that understands
PDF 1.1.

> What changes has Adobe been making? Are they important?

They're documented in the spec. I'm not familiar with all of them. I don't
think any of them other than the binary format introduced in PDF 1.1 are
critical to my purposes, although "linearization" makes the file more
friendly to web browsers.

> Is there a bottom line and lowest common denominator PDF?

Hard to say. So far the only flames I've received have been about using
the PDF format in general, not about my use of a specific version.

> What PDF does Ghostscript output?

No idea. But I wouldn't use Ghostscript for scanned images. I go straight
from TIFF Class F Group 4 to PDF.

Received on Tue Mar 09 1999 - 19:14:32 GMT

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