[IPP] Requested Additions to PWG Raster

[IPP] Requested Additions to PWG Raster

[IPP] Requested Additions to PWG Raster

Petrie, Glen glen.petrie at eitc.epson.com
Fri Apr 22 14:35:10 UTC 2011

I would like to request two additional optional fields be added to the
PWG Raster.  Since they are new to even CUPS raster they would need to
be reserved in the field known as "cupsInteger".  So, while the fields
would be optional to fill in, the fields need to be reserved in the
header definition .


I have found that is useful to have the size of the raster data and to
have the raster data that is uncompressed (, at least temporarily); thus
a compressed state flag is useful.


Once the PWG Raster is used by clients and printer, it will most likely
be used more universally by transforms and other processes (previews,
etc.) .  Currently is difficult to navigate the PWG Raster pages because
the size of the (compressed) raster is unknown; therefore, therefore,
the entire raster file must be serially decompressed to move from one
page to the next.  While I realize, for some resource limited device, it
is not possible to know the size of the (compressed) raster before
sending the data, it is very useful for both navigation and check if the
size of the (compressed) raster is known.   Being optional, if the size
information is not known then the field has value of zero.


For most (all) processing, the raster data needs to be decompressed.
(For transport it should also be compressed.)   Therefore, it convenient
to have the raster page data to be uncompressed; versus decompressing
and compressing between processes.    To denote this, a state flag is
needed.   This is also an optional field and the value of zero (0) means
the data is compressed.   I would not waste a whole integer on a flag,
therefore, I would propose that one of the cupsInteger be reserved for




cupsInteger[0:0] = Compressed (0)/Decompressed(1) raster data

cupsInteger[1]    = PageCount (as proposed by Michael Sweet below)

cupsInteger[2]    = Size, in bytes, of a (this) raster data (compressed
or uncompressed size)






Lasted additions posted by Michael Sweet

1.	PWG Raster Review 

	b.	Issue: Would be nice to have total page count (if known)

		*	Proposal: Add PageCount (integer, 0 to 2^31-1)
to page header ("cupsInteger[0]" from CUPS Raster), which is already
used by several CUPS Raster printer drivers 
		*	0 means "I don't know how many pages" 
		*	> 0 means "this is how many pages are in the
entire document" 
		*	Every page gets the same value 

	c.	Issue: Need coordinate space of image (flip/rotate on
back side) 

		*	Proposal: Add HorizontalTransform(integer, -1 or
1) and VerticalTransform(integer, -1 or 1) to the page header
("cupsInteger[1]" and "cupsInteger[2]" from CUPS Raster) 
		*	"Normal" pages have values of 1 and 1 
		*	"Rotated" pages have values of -1 and -1 (180
degree rotation) 
		*	"Flipped" pages have values of 1 and -1
(vertical flip) or -1 and 1 (horizontal flip) 

	d.	Issue: Need bounding rectangle of any content to be
imaged on the page (ImageBox) 

		*	Proposal 1: * Use existing ImagingBBox (4 x
integer) from page header - simple bounding box in (integer) points 
		*	Proposal 2: Add ImageBottom (integer, 0-2^32-1),
ImageLeft (integer, 0-2^32-1), ImageRight (integer, 0-2^32-1), and
ImageTop (integer, 0-2^32-1) to the page header ("cupsInteger[3]"
through "cupsInteger[6]" from CUPS Raster) - simple bounding box in

	e.	Issue: Some confusion about why we need

		*	Will be adding explanatory text to the
		*	Basically supported raster resolutions can be
different than supported hardware resolutions 

	f.	Issue: Some confusion about the compression algorithm 

		*	Will be adding examples for 1-bit grayscale and
32-bit CMYK images to clarify 
		*	Also have sample raster files available for

	g.	Samples files: 

		*	Currently at
		*	40MB download, 80MB worth of data 
		*	150dpi files for black-1, cmyk-8, sgray-8,
sgray-16, srgb-8, and srgb-16 
		*	Representative documents for email, line art,
maps, photos, and web pages 
		*	Issue: Where to place sample raster files? 


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