Re: needed picture format (was: Re: Amaya 1.3b)

> No: PDF is an approach for distributing documents, not for web pages. A
> web page is one page at a time to be seen in a brouwser, where pdf is
> aimed at documents of more than one page to be printed on your local
> printer.

Just as HTML has moved towards being a page description language, PDF 
has moved to being a web site language.  On a system that supports 
HTTP byte ranges, you can fairly efficiently access PDF a page at a 
time from the server.  My main point, though, was that most 
commercial web page designers are trying to create page descriptions, 
not revisable, logical document structures, as a result, they are 
fighting HTML to get a controlled layout.

> > PDF is Postcript minus programming but with file structuring for
> > fast navigation.  It still has the same primitive graphic operations,
> > but they have to work on numbers, not expression.

> NO: try to read any postscript in your favorit editor, it will not
> complain about characters outside the readable ascii range where a pdf
> file contains binary data.....

There is nothing that intrinsically requires a PDF file to contain 
binary data, and, in fact, PDF 1.1 format files created by 
ghostscript are pure text, except for the comment, at the beginning,
designed to trick mail programs into treating them as binary, and any 
bit mapped images.  (PDF 1.2 allows the unpatented deflate algorithm,
so these are compressed by ghostscript.)

Conversely, although baseline postscript is printable, there is 
nothing to stop one using exactly the same compression filters as 
used by PDF.  Note that the binary nature of PDF comes from the 
compression; the uncompressed data uses printable format numbers.
The compression is compress or zip type compression, not binary 
coding of values.

The structuring information in PDF (location of objects) does rely on 
exact character offsets, so requires that no DOS/Unix/Mac end of line 
conversions are done.

This is a fragment of a valid real PDF file containing vector 
graphics (m is move, l is line) in text format.

%PDF-1.1
%This line contains top bit set characters - I've removed them to
%avoid going to quoted printable mode.  The top bit set characters 
% only there to force binary handling by mail programs
4 0 obj
<</Length 5 0 R>>
stream
0.1 0 0 0.1 0 0 cm
q
1 i
1 w
q 6.43765 0 0 6.45442 0 0 cm
528.976 958.935 62.9921 7.99998 re
S Q
q 10 0 0 10 0 0 cm BT
/R6 5.79388 Tf
1 0 0 1.00261 355.177 621.519 Tm(10m)Tj
ET Q
0.74902 1 0.74902 rg
1345.31 1645.46 m
1335.01 3287.46 l
1391.66 3287.46 l
1396.81 6437.22 l
4018.22 3881.27 l
4059.42 1748.73 l
2390.79 1697.09 l

-- 
David Woolley - Office: David Woolley <djw@bts.co.uk>
BTS             Home: <david@djwhome.demon.co.uk>
Wallington      TQ 2887 6421
England         51  21' 44" N,  00  09' 01" W (WGS 84)

Received on Monday, 19 October 1998 08:18:48 UTC