[IPP] Requested Additions to PWG Raster

[IPP] Requested Additions to PWG Raster

[IPP] Requested Additions to PWG Raster

Rich Gray rgray at plustechnologies.com
Mon May 2 16:32:46 UTC 2011

Ok, I'll wander in from the peanut gallery and probably expose my
ignorance.  I've only been following these festivities loosely, but the
posts about total pages and then then the desire for a compressed size
did catch my attention.   Looking over
<ftp://ftp.pwg.org/pub/pwg/ipp/wd/wd-ippraster10-20110327-rev.pdf>  ,
from a server perspective, it bothers me greatly that it is not possible
to find and extract pages from this format without uncompressing the
images out to the desired page(s).  Yes, the server will probably have
the resources (disk and processor) to accomplish this, but given these
are by definition large files, it seems like a bloody waste.   If this
is to become a widely used format, then ideally, it should be possible
for a server to ingest and send these pages on their way with minimal
overhead, unless the server really has to do some sort of reformatting.
I see two possibilities to make it easier on servers:
1. chunk the data
2. take a page from the PDF format and write the size of the preceding
image data into a field in the FOLLOWING page header.  This would
require some sort of trailer record on the file.   With this, a server
could run backwards through the file, stepping from header to header and
with low overhead find any desired page in the file.  
My humble $.02
Richard B. Gray
Senior Software Engineer
Plus Technologies LLC
444 Alexandersville Road
Miamisburg, OH 45342-3568
+1 937-847-0614 ext. 2405
+1 937-384-0842 fax
877-899-7587 toll free
rgray at plustechnologies.com


From: ipp-bounces at pwg.org [mailto:ipp-bounces at pwg.org] On Behalf Of
Petrie, Glen
Sent: Friday, April 22, 2011 1:33 PM
To: Michael Sweet
Cc: ipp at pwg.org
Subject: RE: [IPP] Requested Additions to PWG Raster

As stated below, I do understand objection to adding the field.  I would
to hear from other PWG members on the addition of these fields.






From: Michael Sweet [mailto:msweet at apple.com] 
Sent: Friday, April 22, 2011 10:20 AM
To: Petrie, Glen
Cc: ipp at pwg.org
Subject: Re: [IPP] Requested Additions to PWG Raster


On Apr 22, 2011, at 9:34 AM, Petrie, Glen wrote:



	[gwp] The important case is the size of the compressed raster
data. The decompressed size is recorded only if the raster is

	[gwp] I agree that some (a few or a lot) of implementation may
not provide the information but as I said, I am requesting that the
assignment be made and those who can (want to) may record the size


It really isn't a matter of "may not provide", in most cases clients
(and printers) simply can't buffer hundreds of megabytes of raster data.
I can add the field, but since most producers of PWG Raster will not be
able to supply the compressed size of the raster no printer will be able
to depend on it anyways, so IMHO it is best to have the printer, if it
is going to do any local processing of full page images, use its own
optimal internal storage format than try to gerry-rig something into the
format that just won't work.


[gwp] As I stated in my original request, I am not worried about the
printer, it will accept the streaming input just fine.  I want the size
information for navigation of a many page raster without having to
decompress pages in a serial manor.   I am not jerry-rigging anything.
I do not understand your comment "that just won't work".  It works fine.
In fact, I wrote a routine that will find the size-only of compressed
page by running the compression routine without storing the compressed
data.  I don't understand your objection to assigning the field.



	I would actually prefer to flag the file as version 3 which is
an uncompressed CUPS Raster with the version 2 page header. And in the
case of local processing, you'll likely want to use native word order
(another feature of CUPS Raster that we are not bringing along for PWG


	[gwp] Do you mean big/little-endian?  I am nothing requesting
the word ordering flag (value) be used.  The current specification is


My main point was that if you are concerned about having a standard
representation for intermediate data, CUPS Raster already provides that.
If you are trying to tweak PWG Raster for use as an internal
representation format then I'd rather not put that in the standard since
internal formats are OOS for any PWG standard.

Would it be sufficient to document an uncompressed version of PWG Raster
(with the "RAS3" file header) and then mark the native word order
support as out-of-scope for the spec but something that might be used


[gwp] I believe the RAS3 is for the entire PWG Raster file.  I am
requesting a flags (value) for individual pages.  


Since the format does not support this, I would be opposed to adding
something that would be used only for an internal representation of a
PWG Raster file.


[gwp] Again, I do not understand your objection. 


Michael Sweet, Senior Printing System Engineer, PWG Chair


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