Hi Glen,
I see the logic of your comments.
But IPP/2.0 Second Edition *did* specifically resolve this
"quality" versus "resolution" question based on quite a lot
of mailing list and face-to-face discussion. This is stated
in on page 21, section 6.2, item 8 of PWG 5100.12.
So a conforming IPP Printer has to behave accordingly.
We can add more discussion in IPP JPS3, if that seems
appropriate, but we really can't reverse the IPP/2.0 SE,
because that would not be backward compatible.
Cheers,
- Ira
Ira McDonald (Musician / Software Architect)
Chair - Linux Foundation Open Printing WG
Secretary - IEEE-ISTO Printer Working Group
Co-Chair - IEEE-ISTO PWG IPP WG
Co-Chair - TCG Trusted Mobility Solutions WG
Chair - TCG Embedded Systems Hardcopy SG
IETF Designated Expert - IPP & Printer MIB
Blue Roof Music/High North Inc
http://sites.google.com/site/blueroofmusichttp://sites.google.com/site/highnorthinc
mailto:blueroofmusic at gmail.com
Winter 579 Park Place Saline, MI 48176 734-944-0094
Summer PO Box 221 Grand Marais, MI 49839 906-494-2434
On Thu, Feb 2, 2012 at 10:06 AM, Petrie, Glen <glen.petrie at eitc.epson.com>wrote:
> Mike,****
>> ** **
>> Interesting but I still believe my conclusions support both a simple and
> sophisticated user-centric model. A simple user-centric model will always
> use the “quality” setting and, for added “control”, will set “content type”
> to get the desired output. Sophisticated users will want to control the
> finer details and, thus, may want a specific resolution. ****
>> ** **
>> As to “draft” operations or any other quality setting operations: in
> general, no print vendor is going to use simpler/faster dithers or
> color-transform or not perform print row interleaving, if it reduces the
> overall printed quality of the output simply because the user set quality
> setting to draft/normal/high in a Print Client. There would be
> insignificant amount of processing required; no need to support multiple
> dither/color transforms routines; and an unnoticeable amount of additional
> (if any) overall print time. If a user specifies a resolution versus
> quality; then, saving ink was not his/her intent; he/she wants a specific
> resolution for his/her specific reason. While bi-directional versus
> uni-directional printing are affected by quality settings; print service
> internal selection (not user set) would also use content-type (for example;
> high-quality text (bi) versus high-quality photo(uni)) which, of course, bi
> versus uni, can also be done as a function of resolution and the
> content-type.****
>> ** **
>> The constraint is solved by;****
>> ** **
>> 1. The content-type MUST be set; ****
> 1. The default could be “text and graphic”****
> 2. If user sets resolution; then the Print Services uses this
> resolution along with content-type. The Print Service will ignore any
> quality-setting and set any internal processing based on resolution and
> content-type only. ****
> 1. If the resolution set is not supported; then return an error.
> (How this could occur from a print client that received printer capability
> data is unknown but just in-case the user is allowed to “type” in any
> resolution they want!) ****
> 3. If user set quality but not resolution, then****
> 1. The Print Service uses content-type and quality-setting to
> determine a resolution and internal processing.****
>> ** **
>> IMHO, the user must always be in control. Setting resolution is more
> specific than setting quality, since quality is qualitative versus
> quantitative; thus, if a user sets a resolution; then that what should be
> done. ****
>> ** **
>> I think we will have to agree to disagree and simply move on!****
>> ** **
>> glen****
>> ** **
>> ** **
> ------------------------------
>> *From:* Michael Sweet [mailto:msweet at apple.com]
> *Sent:* Wednesday, February 01, 2012 5:00 PM
>> *To:* Petrie, Glen
> *Cc:* mfd at pwg.org> *Subject:* Re: [MFD] Question on Resolution Versus Qaulity
> ****
>> ** **
>> Glen,****
>> ** **
>> On Feb 1, 2012, at 3:45 PM, Petrie, Glen wrote:****
>> 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.****
>> ** **
>> "Draft" might select (for example) bidirectional printing on an inkjet
> with no interleaving of dot rows. It could also use a simpler/faster
> dithering algorithm, simpler/faster color transform, use less inks (i.e.
> just CMYK instead of CMYKcmk), etc.****
>> ** **
>> [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!****
>> ** **
>> Users do not know how quality and resolution interact, and in the absence
> of the JPS3 mechanisms for doing constraint resolution there is no way for
> the client to know either.****
>> ****
>> 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!****
>> ** **
>> and if that resolution is supported by the printer then by all means it
> should use it! But if not, the printer should let the client know it can't
> use that resolution and use the closest resolution instead...****
>>>> ****
>> [gwp] The conclusion is then****
> ******
>> ******
>> 1. Specified Resolution wins over “Quality” - always, since the User
> specified ‘use this resolution”.****
>> ** **
>> The user specified "use this quality". One has to win, and IMHO (and based
> on what we agreed to and approved in IPP/2.0 SE) Quality wins over
> Resolution.****
>> ** **
>> ****
>> 1. ** **
> 2. Content-Optimize MUST be required – for a printer to properly
> determine the correct resolution when resolution is not specified.****
>> ** **
>> That's what defaults are for...****
>>>> ****
> ****
>> 1. ** **
> 2. Print-Quality is [Quality (-Intent) + Content-Optimize ] or [
> Resolution] but not both.********
>> ** **
>> Again, these elements are related but not mutually exclusive.****
>> ** **
>> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair****
>> ** **
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