Am 21.12.2021 um 15:51 schrieb Peter Kronenberg:
Running the attached PDF file through TIKA, I get a lot of garbage in
the output (see txt file). Far more than can be explained by the
unmapped characters. Where is this coming from?
After the character is found to be unmapped, PDFBox tries a backup
strategy, which is obviously not successful here.
// when there is no Unicode mapping available, Acrobat simply
coerces the character code
// into Unicode, so we do the same. Subclasses of
PDFStreamEngine don't necessarily want
// this, which is why we leave it until this point in
PDFTextStreamEngine.
if (unicode == null)
{
if (font instanceof PDSimpleFont)
{
char c = (char) code;
unicode = new String(new char[] { c });
}
else
{
// Acrobat doesn't seem to coerce composite font's
character codes, instead it
// skips them. See the "allah2.pdf" TestTextStripper file.
return;
}
}
Adobe Reader has also trash.
I can't comment whether it is "far more than expected", this would
require to count and make comparisons.
If I take the PDF and flatten it by ‘printing’ to a PDF file, the
garbage goes away
Printing is probably converting it all to raster graphics or vector
graphics.
Tilman
