PDF and PNG images

[mm...@arcus.com.au]

Am I correct in saying that PNG images cannot be embedded in native form
in PDF files, i.e. the PDF format does not support the appropriate filters
for PNG, or is the current FOP behaviour of storing PNG images
decompressed a FOP limitation?

My customer deals a lot with PNG images and at least from where they
source them from the PNG images are significantly smaller than the
equivalent JPEG images.

So the question is: Is there an efficient means of embedding PNG into PDF
or are we stuck with converting to JPEG first?

Thanks

Manuel



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Re: PDF and PNG images

[Jeremias Maerki <de...@jeremias-maerki.ch>]

Yes, PDF cannot embed PNG images directly. However, there appears to be
certain provisions in PDF 1.4 for "PNG predictors". But I didn't look
into what this means exactly. I only know that PNG is largely based on
zlib compression with some extensions probably to improve compression
rates. If you're serious about it I'd look into the PDF 1.4 spec and
make sense of these PNG predictors.

Are you saying that the normal flate (zlib) compression FOP can apply to
images isn't sufficient to get more or less the same compression rate as
with PNG images?

On 28.06.2006 07:23:43 mm wrote:
> Am I correct in saying that PNG images cannot be embedded in native form
> in PDF files, i.e. the PDF format does not support the appropriate filters
> for PNG, or is the current FOP behaviour of storing PNG images
> decompressed a FOP limitation?
> 
> My customer deals a lot with PNG images and at least from where they
> source them from the PNG images are significantly smaller than the
> equivalent JPEG images.
> 
> So the question is: Is there an efficient means of embedding PNG into PDF
> or are we stuck with converting to JPEG first?

Jeremias Maerki


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