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Topic: RE: Compressed PDF display blank page in Reader 7 but ok in 6/5 (Via Email)
Conf: (P-PDF) Acrobat 7, Msg: 126246
From: ldefurio
Date: 1/25/2005 01:16 PM

That is correct. Adobe Reader conforms to the PDF Specification. If PDFs are
do not conform to the PDF spec - they may not open in Adobe Reader.

Another example of PDF that was not written to match the specification.

According to the PDF Specification, the Length attribute is required (I put
some quotes below.) And the Stream Extent discussion indicates everything
has to be consistent -- the length of the data has to match the Length
attribute.

TABLE 3.4 Entries common to all stream dictionaries

KEY TYPE VALUE

Length integer (Required) The number of bytes from the beginning of the line
following the keyword stream to the last byte just before the keyword
endstream. (There may be an additional EOL marker, preceding endstream, that
is not included in the count and is not logically part of the stream data.)
See "Stream Extent," above, for further discussion.

From Page 37:

Stream Extent

Every stream dictionary has a Length entry that indicates how many bytes of
the PDF file are used for the stream's data. (If the stream has a filter,
Length is the number of bytes of encoded data.) In addition, most filters
are defined so that the data is self-limiting; that is, they use an encoding
scheme in which an explicit end-of-data (EOD) marker delimits the extent of
the data. Finally, streams are used to represent many objects from whose
attributes a length can be inferred. All of these constraints must be
consistent.

For example, an image with 10 rows and 20 columns, using a single color
component and 8 bits per component, requires exactly 200 bytes of image
data. If the stream uses a filter, there must be enough bytes of encoded
data in the PDF file to produce those 200 bytes. An error occurs if Length
is too small, if an explicit EOD marker occurs too soon, or if the decoded
data does not contain 200 bytes.

It is also an error if the stream contains too much data, with the exception
that there may be an extra end-of-line marker in the PDF file before the
keyword endstream.

-----Original Message-----
From: p-pdf-acrobat7 Listmanager
[mailto:p-pdf-acrobat7.listmanager@forum.planetpdf.com]
Sent: Friday, January 21, 2005 8:51 AM
To: Recipients of 'p-pdf-acrobat7' suppressed
Subject: Compressed PDF display blank page in Reader 7 but ok in 6/5

From: "Erling"

--------- Planet PDF Forum | http://forum.planetpdf.com ----------

Forget about this. It's an error in my PDF-document. Reader 7.0 requires the
length attribute to be set correctly. Reader 5/6 does not...





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