Strange behaviour of file in !PDF
Nat Queen
but not in our !PDF (I have !PDF 3.00.1.17). The file contains only
plain English text - no unusual symbols.
When viewed in !PDF, each character is replaced by a different one, as
if a simple Caesar cipher has been applied. For example, the word
"available" appears as "DYDLODEOH" - with each ASCII value reduced by
29 (but characters with lower ASCII values such as numerals 1-9 are
shifted upward to top-bit characters.
Has anyone ever seen anything like this? Is there a cure for this?
The file is viewable normally when using !GhostScr/!GView - but this
is less convenient, being slower to process each page.
Any ideas?
Nat
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Martin Wuerthner
Nat Queen <n.m....@bham.ac.uk.invalid> wrote:
> Someone sent me a PDF file, which can be viewed normally in Windoze,
> but not in our !PDF (I have !PDF 3.00.1.17). The file contains only
> plain English text - no unusual symbols.
> When viewed in !PDF, each character is replaced by a different one, as
> if a simple Caesar cipher has been applied.
Yes, that is more or less what is happening here.
> For example, the word "available" appears as "DYDLODEOH" - with each
> ASCII value reduced by 29 (but characters with lower ASCII values such
> as numerals 1-9 are shifted upward to top-bit characters.
This is caused by the file using an embedded subset TrueType font,
i.e., a font that contains only the glyphs that are used in the file,
represented by a compact range of character codes. The code points
have been rearranged accordingly. !PDF does not interpret embedded
TrueType fonts at all and renders the character codes using a
substitute font, but the mapping from code points to actual characters
is part of the embedded font, which is ignored.
> Has anyone ever seen anything like this? Is there a cure for this?
Yes, using a PDF viewer that can interpret embedded TrueType fonts,
such as Ghostscript/GView, as you found out.
> The file is viewable normally when using !GhostScr/!GView - but this
> is less convenient, being slower to process each page.
Martin
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