[IPP] (PWG) Raster Question on what is required

[IPP] (PWG) Raster Question on what is required

[IPP] (PWG) Raster Question on what is required

Petrie, Glen glen.petrie at eitc.epson.com
Thu Apr 28 17:21:35 UTC 2011




From: Michael Sweet [mailto:msweet at apple.com] 
Sent: Thursday, April 28, 2011 10:09 AM
To: Petrie, Glen
Cc: ipp at pwg.org
Subject: Re: [IPP] (PWG) Raster Question on what is required


On Apr 28, 2011, at 9:51 AM, Petrie, Glen wrote:


	In the (PWG) Raster, the specification states support for
16-bits per color.  TIFF seems to the only image file format supporting
it and even the TIFF libraries I could find only support up to 8-bits
per color.


libtiff (the most widely-used TIFF library) supports 16-bits per color.


I must be looking at the wrong version because TIFF 6.0 shows only
<8,8,8> http://www.libtiff.org/support.html 

While I believe the (PWG) Raster specification indicates the range of
possible values; will or is there is a specification or compliance
requirements on what must be supported?  (The same would apply to color


I thought I had included this, but couldn't find any requirements in the
PWG Raster or IPP Everywhere specs.


Not in (PWG) Raster spec (I believe it would in section 4.3.4 or is
there another section)

The conformance section (6.x)  the "MUST" for attributes but not for


My thought was to require sgray-1 and sgray-8 for all printers and
srgb-8 for color printers. 


Sound good to me.



	Or is the situation that the printer provides it capabilities,
which must be one or more of the of the (PWG) Raster values.  Thus,
there are no mandatory values just a possible range of supported values.


I think for interoperability we want a minimum set for interoperability
(and to address the use cases/design requirements). But most values of
color space and bit depth should be optional.


Ok, then from your color-spaces, the required bits-per-color would 1 and
8.  Also, the required bits-per-pixel would be 1, 8, 24


One more time.  Does conformance to pwg-raster-back-side mean "the
printer will perform the indicated transforms" or this is an identifier
stating what the "state" of the back-side image is?





Michael Sweet, Senior Printing System Engineer, PWG Chair


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