Conceptually there is no reason a printer could not support a draft mode
for multiple resolutions (and this is in fact the case in CUPS/Mac OS
X), so preventing both from being specified will do a disservice to the
user and printer/driver.
[gwp] So if we have "draft" at 75, 150, 300; and the user can select
both "draft" and 300; then what is the value of "draft" to the Print
Service since the Print Service was told to print at 300 dpi.
[gwp] Users are more likely to select "quality" equals "draft" and
"contentOptimize" equals "photo" and not a dpi (ops: resolution). If a
user 'really understands' the Print Service performance for differing
dpi's (again ops: resolution's); then "quality" should never win because
the user knows exactly what dpi they want!
Quality != Resolution. They may be related, and there may in fact be
constraints that cause a particular combination to conflict, but they
are not mutually exclusive and express separate intent. The IPP/2.0
recommendation to prefer Quality over Resolution when there is a
conflict is a pragmatic approach to automatic conflict resolution.
[gwp] Print-Resolution is a function of both Quality AND
Content-Optimize. Any printer today can determine a resolution from
these two values. If a user specifies a resolution then the Print
Service should use the resolution (resolution is always the winner)
since the user is stating they want the specified resolution that gives
them a desired quality for the content!
[gwp] The conclusion is then
1. Specified Resolution wins over "Quality" - always, since the
User specified 'use this resolution".
2. Content-Optimize MUST be required - for a printer to properly
determine the correct resolution when resolution is not specified.
3. Print-Quality is [Quality (-Intent) + Content-Optimize ] or [
Resolution] but not both.
Glen
On Feb 1, 2012, at 3:02 PM, Petrie, Glen wrote:
Mike, Pete, (All)
So, should the PJT not specify both but rather specify one or the other?
I know that for the PJT, that "quality" is required while "resolution"
is optional. So if "quality" is required and always wins; what is the
value or need for "resolution"? The spec's do not have a value of
"unknown" or "other" for "quality"; so, the Print Service will not ever
use the "resolution" information and, in fact, the "resolution" data
simply adds confusion.
However, if "quality" and "resolution" were made either-or-but-not-both,
then a client could specify either without a "winner". The other
option is add the values "unknown" or "other" to "quality" which directs
the Print Service to use "resolution".
Glen
________________________________
From: Michael Sweet [mailto:msweet at apple.com]
Sent: Wednesday, February 01, 2012 12:52 PM
To: Petrie, Glen
Cc: mfd at pwg.org
Subject: Re: [MFD] Question on Resolution Versus Qaulity
Glen,
This is covered in IPP/2.0; basically if there is a conflict between
resolution and quality, quality wins.
As far as PWG Raster goes, that is a separate capability
(PwgRasterDocumentResolutionSupported) that expresses the capabilities
of the input side of the printer's imaging engine, while Resolution
expresses the capabilities of the output side of the printer's imaging
engine.
(i.e. a printer might only accept 360dpi raster data but print it at
2880dpi...)
On Feb 1, 2012, at 8:52 AM, Petrie, Glen wrote:
Pete (All),
I remember a discussion about resolution versus quality (I think the PWG
raster discussions). I thought that is quality and resolution did not
agree (as interpreted by the print service capability/definition) then
quality was to be used. In the PJT should resolution and quality be
denoted as either but not both? Or at least should a note be added?
Glen
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