[IPP] PDF Raster and IPP Scan

[IPP] PDF Raster and IPP Scan

[IPP] PDF Raster and IPP Scan

Michael Sweet msweet at apple.com
Tue Sep 5 12:44:10 UTC 2017


As this is a strict subset of PDF and IPP Scan requires PDF support, nothing needs to be added unless you want the Client to be able to explicitly ask for a particular subset of PDF...  We could add a pdf-versions-supported keyword, but that is strictly informative...

That said, this subset is almost exactly the same as the PDF/is specification the PWG published 13 years ago:


The main differences appear to be:

1. No JBIG2 support (?!?)
2. Different file format identification methods: PDF/is adds a new object, while PDF Raster uses a comment in the trailer.
3. PDF Raster supports encryption while PDF/is does not, but that doesn't really matter - PDF encryption is a joke because key generation is weak.
4. PDF Raster adds an XML (Adobe XMP) metadata object.

Both PDF/is and PDF Raster support banding, digital signing, and incremental/streamed writing.  Both also support the same bi-level, grayscale, and RGB color color spaces and bit depths.

The PDF Raster spec claims that it can be consumed by a simple parser, but I don't see how given that images can be banded - you will still need to implement a minimal page stream interpreter along with random access to the image objects.

Finally, it looks like a PDF writer could generate a PDF file that conforms to BOTH PDF/is and PDF Raster - thus an IPP Scan implementation could (as part of the general PDF support requirement) produce PDF scan files compatible with both standards.  But again, I don't think we need to update IPP Scan for this...

> On Sep 1, 2017, at 8:34 AM, Paul Tykodi <ptykodi at tykodi.com> wrote:
> Hi,
> I saw this announcement this morning.
> Should we consider adding support for this format in IPP Scan?
> http://www.prweb.com/releases/2017/08/prweb14644230.htm
> Best Regards,
> /Paul
> Sent from my iPhone
> _______________________________________________
> ipp mailing list
> ipp at pwg.org
> https://www.pwg.org/mailman/listinfo/ipp

Michael Sweet, Senior Printing System Engineer

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