Hi John,
At yesterday's IPP Fax telecon, we discussed all of your comments.
Brief replies to the best of my abilities are included in your note
below, preceded by '<ira>'.
Cheers,
- Ira McDonald, consulting architect at Sharp and Xerox
High North Inc
-----Original Message-----
From: McDonald, Ira [mailto:imcdonald@sharplabs.com]
Sent: Wednesday, June 27, 2001 11:55 AM
To: 'ifx@pwg.org'; Thomas, John; Whittle, Craig
Subject: IFX> FW: [Comments on UIF spec]
Hi folks,
Here are comments from my colleague John Thomas at Sharp on UIF spec.
We should consider them at this afternoon's telecon, if we have time.
Cheers,
- Ira McDonald, consulting architect at Sharp and Xerox
High North Inc
-----Original Message-----
From: Thomas, John
Sent: Tuesday, June 26, 2001 5:36 PM
To: McDonald, Ira
Cc: Thomas, John; Olbricht, Eric; Whittle, Craig; Koss, Scott; Murdock,
Joe; Hurtz, Robert
Subject: RE: IFX> IPP FAX telecon agenda, Wed, June 27, 10-12 PDT (1-3
EDT)
Ira -
Most of my questions and observations are about Universal Image Format (UIF)
specification.
1) The text fields for "ImageDescription", "DocumentName", "Software" and
"DateTime" all use ASCII encodings. As we have discussed in the past, this
limits these fields effectively to US English. (Is there an encoding for the
British pound symbol in 7-bit ASCII?). Is this an oversight, or is this
because of UIF's TIFF-FX/ITU legacy?
NOTE: IPP-Fax identifies the "native language", at least for notification.
<ira>
Adobe Baseline TIFF specified ASCII only and didn't provide a language
tag or alternate charset facility. Too bad, but UIF docs MUST be strictly
compliant Adobe Baseline TIFF.
A note will be added to the UIF spec about this limitation.
The companion IPP Fax spec will explicitly say that the (localized)
IPP job attribute 'document-name' SHOULD be used in preference to
the TIFF 'DocumentName' field.
'DateTime' doesn't need to be localized (it's a document create timestamp),
because it can be localized by a client without problem.
<--->
2) What is the intended use for the "DateTime" field? Creation date? If
so, it would be nice if the specification stated this. If an image has a
creation date, shouldn't it also have an author/copyright holder field?
Yes, I know this would be easy to edit out, but that would be a felony.
Right? :-)
<ira>
Yes - it's a document creation date/time.
No - we cannot change the semantics of 'DateTime' to add author.
<--->
3) The UIF spec expects the name and revision of the authoring software in
the "Software" text field. I assume this text is format-free? Human
readable (that is, if you are an English speaking human). And while we are
on the subject of "Revision", shouldn't the specification identify its own
revision? This is a common technique to provide "future backward
compatibility".
<ira>
This is Baseline TIFF legacy. Human-readable in some language that
can be written in ASCII without any accented Latin characters.
<--->
4) Why do profiles C, F and J (optionally) allow centimeter resolution
units, but profiles L and M only allow "inch" resolution units? TIFF-FX
again? Again I ask, how would this specification change if the United
States FINALLY went metric? Is there a reason to prohibit cross-unit
compatibility like, for example, the computational cost of a good
sub-sampling algorithm?
<ira>
There are some typos on your list above. The b&w TIFF-FX profiles allowed
centimers or inches. The color TIFF-FX profiles used inches because
that's what the engine builders did at the time the TIFF-FX profiles
were specified. For interoperability, UIF will NOT relax this
restriction - gateways to Internet Fax and ITU GSTN fax are high
priority.
<--->
5) Do all (international) bitmap format standards order scan lines
left-to-right and top-to-bottom? If not, is there a need for UIF to specify
this order? This scan-line order inherited from the base formats (e.g.
TIFF-FX)?
<ira>
Adobe Baseline TIFF specifies the scan lines order.
<--->
6) I prefer the presentation of compliance requirements in the IPP-Fax
specification to that in the UIF specification. IPP-Fax makes it clear what
is "receiver" responsibilities and what is "sender" responsibilities. UIF
doe not.
<ira>
Improvements in specification of compliance requirements will be done
in the UIF spec.
<--->
7) Line 152 of the IPP-Fax specification says: "Universal Interchange Format
(UIF)". I think it should say "Universal Image Format (UIF)".
<ira>
Done - Tom Hastings has it in his edits list.
<--->
Please pass on to the appropriate authorities any of these thoughts which
have any merit.
Thanks.
John
jct@sharplabs.com
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