We need to understand better where conversion from inches to mm or vice
versa might occur.
As I said in a previous mail message, the Media Size Self Describing Name is
really a keyword, not a name and not a set of attribute values.
I don't think that we expect that the Media Size Self Describing Name tokens
would be send from client to printer or printer to client using either form
of units for a given size. In other words, we don't expect that a Printer
would support both:
na-letter.8500-11000
letter.2159-2794
So only the first value is needed for interoperability between client and
Printer.
We probably need to add a note about *not* having both forms for the same
size (either in the standard or in actual interchange), judging from the
confusing that this email discussion is showing.
Instead, these tokens are really keywords and the proper units are sent for
the size, even if the user is running in the opposite locale. Sure a good
client will be displaying the sizes to the user in the units that the user
has set for his locale (inches or mm). But we don't want to double the
number of tokens, by having both an English version and a metric version.
Mark indicates that the Driver (or Printer) might keep all dimensions
internally in only one set of units. That is a good implementation
technique (but outside the scope of our Media standard). I'd suggest that
for such an internal implementation is where 100th of mm is a good bet, to
avoid the round off problem. But our Media Standardized Names is NOT
specifying how client and printers represent things internally, but how they
interchange between each other. (Similarly, our standard is also *not*
specifing how a client displays our names to the user).
I'm not sure we even have a problem for custom sizes, though it isn't so
clear.
Two cases:
a. The Administrator defines the custom sizes that his shop/printer has.
b. The user defines the custom sizes that he/she wants, whether or not the
shop/printer has them.
In the a case, the Administrator would use the units that his users were
most likely know. He might have to define the same custom size in both sets
of units, if he was in a local that had both English and Metric users. But
that's a conversion he does when he defines the sizes, its not an algorithm
performed by some software.
In the b case, the European user would want to specify the custom size in mm
(and the client converts to 1/10 mm before sending to the Printer), while
the North American would want to specify the custom size in inches (and the
client converts to 1/1000 inches before sending to the Printer).
Again, there doesn't seem to be the need for more precision in the mm case;
1/10 mm seems sufficient.
Comments?
Tom
-----Original Message-----
From: Hastings, Tom N [mailto:hastings@cp10.es.xerox.com]
Sent: Thursday, April 19, 2001 17:01
To: ipp (E-mail)
Subject: FW: IPP> Media Standardized Names - Units
This mail note brings up the conversion issue of the client converting the
media units from one to the other in order to display the units in the
locale of the user.
It was not forwarded to the IPP list.
Tom
-----Original Message-----
From: Mark Hamzy [mailto:hamzy@us.ibm.com]
Sent: Thursday, April 19, 2001 07:18
To: Mark VanderWiele; hastings@cp10.es.xerox.com; Harry Lewis; Pete
Zannucci
Subject: RE: IPP> Media Standardized Names - Units
Here are two examples. There are around 10 or so that I found.
4.375*254=1111.25
10.830*254=2750.82
There is a need to convert from one to another. One case would be that a
driver keeps one units of measurement internally and converts as needed
externally. User interfaces should have the ability to let the user decide
what units of measurement to display in, so you would need to give a letter
form in metric measurement.
I think that both could be acceptable as input. For the metric user,
letter would look like letter.2159-2794. I think that the na- prefix is
akward. It would be better to place it in front of the dimension. Also,
it would allow other units of measurement to be used (twips for example).
Mark
Mark
VanderWiele To: Mark
Hamzy/Austin/IBM@IBMUS, Pete
Zannucci/Austin/IBM@IBMUS,
hamzy@jumpnet.com
04/18/01 06:28 cc:
PM From: Mark
VanderWiele/Austin/IBM@IBMUS
Subject: RE: IPP> Media
Standardized Names -
Units
Regards,
Mark VanderWiele
IBM, Linux Technology Center
512-838-4779, t/l 678
MARKV@IBMUS
email: markv@us.ibm.com
---------------------- Forwarded by Mark VanderWiele/Austin/IBM on
04/18/2001 06:28 PM ---------------------------
HARRY LEWIS
04/18/2001 04:05 PM
To: Mark VanderWiele/Austin/IBM@IBMUS
cc:
From: Harry Lewis/Boulder/IBM@IBMUS
Subject: RE: IPP> Media Standardized Names - Units
Mark, I forget who it was in your office who brought this up. Do they care
to address this?
----------------------------------------------
Harry Lewis
IBM Printing Systems
----------------------------------------------
----- Forwarded by Harry Lewis/Boulder/IBM on 04/18/2001 03:02 PM -----
"Hastings, Tom N"
<hastings@cp10.es. To: Harry Lewis
<harryl@us.ibm.com>,
xerox.com> RonBergman@aol.com
Sent by: cc: ipp@pwg.org
owner-ipp@pwg.org Subject: RE: IPP> Media
Standardized Names -
Units
04/17/2001 06:02
PM
Harry,
There are exactly 254 mm in an inch, so the precision is about the same,
the
inches are about 4 times more precise than the metric units.
For example, the two most popular Self Describing Size Names are:
The letter size (8.5 inches by 11 inches) used in North America:
na-letter.8500-11000
The iso A4 size (210 mm by 297 mm) used in metric countries:
iso-a4.2100-2970
Note that they both have about the same number of digits in each dimension,
namely around 4.
Also there isn't any need to convert from inches to mm or vice versa,
because the paper size is given ONLY in the natural units for the usage.
So
North American sizes only use 1000ths of inches and aren't converted to mm.
Similarly, the non-English sizes are always given in 10ths of mm and aren't
converted to inches. Therefore, there is never any rounding errors to
worry
about.
The only rounding that could occur, is if some paper size is actually in
some fraction of inches, or mm, such as 200 1/3 mm or 10 1/3 inches. But I
don't think we have any sizes like that.
Ok?
Tom
-----Original Message-----
From: Harry Lewis [mailto:harryl@us.ibm.com]
Sent: Monday, April 16, 2001 15:33
To: RonBergman@aol.com
Cc: ipp@pwg.org
Subject: IPP> Media Standardized Names - Units
I'm questioning the use of 1/1000 for English but only 1/10 for metric.
Not only are we loosing precision, but, also introducing rounding errors
during conversion from English to metric . I know the printer MIB heritage
is 1/1000 English and 1/10 metric... but
I think we should try to be more precise in this new media mapping.
----------------------------------------------
Harry Lewis
IBM Printing Systems
----------------------------------------------
RonBergman@aol.com
Sent by: owner-ipp@pwg.org
04/09/2001 02:26 PM
To: <ipp@pwg.org>, <upd@pwg.org>
cc:
Subject: IPP> Fwd: FW: Media Standardized Names, Version
D0.6
is now available
----- Message from "Bergman, Ron" <Ron.Bergman@Hitachi-hkis.com> on Mon, 9
Apr 2001 08:02:14 -0700 -----
To:
"'RonBergman@aol.com'" <RonBergman@aol.com>
Subject:
FW: Media Standardized Names, Version D0.6 is now available
-----Original Message-----
From: Bergman, Ron [mailto:Ron.Bergman@HITACHI-HKIS.COM]
Sent: Monday, April 09, 2001 8:01 AM
To: IMAGING@FORUM.UPNP.ORG
Subject: Media Standardized Names, Version D0.6 is now available
All,
The latest draft is now available at:
ftp://ftp.pwg.org/pub/pwg/media-sizes/pwg-media-06.pdf (or .doc)
I will not repeat the abstract here or the list of changes. This
information is
available within the document, if you are interested. The major change to
this
version is the addition of the "Media Finish Names".
This document will have a final review in the PWG meetings during the week
of April 23rd and should then be ready for last call.
Ron Bergman
Hitachi Koki Imaging Solutions
This archive was generated by hypermail 2b29 : Thu Apr 19 2001 - 21:42:55 EDT