Thanks for the information. I'll look into making the changes to bypass the
decompression for jpegs and just embed the image, without breaking other
stuff hopefully. If it all works out well I'll post may changes.
-Eric Dalquist
----- Original Message -----
From: "Jeremias Maerki" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, August 14, 2001 4:27 PM
Subject: Re: Request: Imbedded Image Compression
> > We have been using FOP in production to generate reports with Oracle's
XSQL
> > servlet for about 1 month now and it has been working great. Our next
> > project is a photo ID class roster. The system is pretty much set but
right
> > now the main thing holding us back is the size of the resulting PDF
> > document. An 8 page PDF with 30 1.5in x 1.13in jpegs on it is 7.18MB.
> > Considering the 240 images used in this document only occupy 730KB this
is
> > rather large. The only other data in the document is a header and each
> > persons name. From what I have read on the FOP mailing list over the
past
> > few months I seem to remember something about the cause of this being
the
> > way Sun's JDK handled the images internally. I was also wondering if
anyone
> > was working on incorporating some kind of image compression into FOP?
>
> Currently all images are decoded into memory as an uncompressed array of
> pixels which then get written (and compressed) to the target file. For
> PDF the compression is ZLib (Flate/Deflate). For JPEG this is very
> inefficient. Theoretically, PDF supports the embedding of native JPEG
> files. This is described in the PDF specs. The clue now would be to
> write code that bypasses the decompression/compression phases that
> happen at the moment. That will probably cause changes in the
> org.apache.fop.image and org.apache.fop.render.pdf packages.
>
> I've once started looking into it but never got enough time to really
> implement it. I'll be away on holidays the next two weeks so I'm not
> much of a help right now.
>
> I can only give some pointers, though:
> - The PDF spec contains information on how to implement JPEG-embedding.
> - JPEG-support in PDF is very similar to JPEG-support in PostScript.
> - And for PostScript there is a demo application on how to embed a JPEG
> image in a PostScript file. This can be easily adapted to PDF. See the
> link below.
> - There's a JPEGReader class that's already parsing the JPEG headers
> (org.apache.fop.image.analyser.JPEGReader).
>
> By the way, your request is already on the todo list.
>
> PDF specs at:
> http://partners.adobe.com/asn/developer/acrosdk/docs.html
>
> JPEG2PS at (in German):
> http://www.pdflib.com/jpeg2ps/
>
> Good luck!
>
> Jeremias Märki
>
> mailto:[EMAIL PROTECTED]
>
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