Re: Proposal for storing ID manifests in OpenEXR headers

Nick Porcino <[email protected]> Tue, 15 Aug 2017 17:59:37 +0000
Newsgroups gmane.comp.video.openexr.devel
Message-ID <DM5PR1601MB13564E83D120816F37E68F58A48D0@DM5PR1601MB1356.namprd16.prod.outlook.com>
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This looks reasonable to me. Almost every question I had was answered by th=
e document,

One part that was unclear was 1.2, which talks about deep pixels and ad hoc=
 encodings in the same paragraph. I feel like I could read 1.2 as deep pixe=
ls are, or are not, supported. I think they would be, but would suggest bre=
aking the discussion of deep and ad hoc apart.

I deduce also that you are proposing ASCII encoding, although I think UTF8 =
should be supported either as the designated encoding or as an option. The =
reason for this is that in my own work I like to designate ids with URI's a=
nd anticipate wanting to encode Japanese strings. Of course I could introdu=
ce my own secondary mapping of exr id to URI at the expense of extra work a=
t my end, but I thought it's worth a bit of discussion.

Similarly, it's not clear to me that a separating character like semicolon =
is necessary to be called out. If the intention is that there will be a set=
 of standard tools that can parse the assignments, I can see the utility, b=
ut the counter examples like "tunic with leather" suggests general parsing =
is perhaps not anticipated.

If semicolon is to be somehow special then I suggest that the manner of esc=
aping semicolon also be described. Could be as simple as ;; or \; means a l=
iteral semicolon, not a separator.

Happy to see new thoughts around EXR,

- Nick p

________________________________
From: Openexr-devel <[email protected]=
> on behalf of Peter Hillman <[email protected]>
Sent: Monday, August 14, 2017 8:23:51 PM
Cc: [email protected]
Subject: [Openexr-devel] Proposal for storing ID manifests in OpenEXR heade=
rs

Hi all,

As Deke mentioned earlier, At Siggraph I presented a proposal for an OpenEX=
R attribute to store ID manifests (i.e. a table that maps between text stri=
ng names of entities and the numerical values encoded in the EXR image) Att=
ached is an updated draft giving more details of this proposal. There are a=
 few modifications from the earlier draft following suggestions from those =
attending Siggraph: many thanks to all those who commented.

This is not a proposed complete single standard for storing IDs within Open=
EXRs. There are reasons to choose one storage scheme over another depending=
 on circumstances, suggesting that it is worthwhile to support different en=
coding schemes. The requirement for an ID manifest is a common requirement =
amongst those schemes. This document merely defines a standard attribute fo=
r encoding the manifest and for allowing it to be compressed. This should a=
llow for a standard set of tools for reading, writing and examining the att=
ribute.

The intention is that I will implement this attribute in the next few month=
s - certainly before the end of the year.  Feel free to comment on the stan=
dard before then!

Peter



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<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dus-ascii"=
>
</head>
<body text=3D"#000000" bgcolor=3D"#FFFFFF">
This looks reasonable to me. Almost every question I had was answered by th=
e document,
<br>
<br>
One part that was unclear was 1.2, which talks about deep pixels and ad hoc=
 encodings in the same paragraph. I feel like I could read 1.2 as deep pixe=
ls are, or are not, supported. I think they would be, but would suggest bre=
aking the discussion of deep and
 ad hoc apart.<br>
<br>
I deduce also that you are proposing ASCII encoding, although I think UTF8 =
should be supported either as the designated encoding or as an option. The =
reason for this is that in my own work I like to designate ids with URI's a=
nd anticipate wanting to encode
 Japanese strings. Of course I could introduce my own secondary mapping of =
exr id to URI at the expense of extra work at my end, but I thought it's wo=
rth a bit of discussion.<br>
<br>
Similarly, it's not clear to me that a separating character like semicolon =
is necessary to be called out. If the intention is that there will be a set=
 of standard tools that can parse the assignments, I can see the utility, b=
ut the counter examples like &quot;tunic
 with leather&quot; suggests general parsing is perhaps not anticipated.<br=
>
<br>
If semicolon is to be somehow special then I suggest that the manner of esc=
aping semicolon also be described. Could be as simple as ;; or \; means a l=
iteral semicolon, not a separator.<br>
<br>
Happy to see new thoughts around EXR,<br>
<br>
- Nick p<br>
<br>
<hr style=3D"display:inline-block;width:98%" tabindex=3D"-1">
<div id=3D"divRplyFwdMsg" dir=3D"ltr"><font face=3D"Calibri, sans-serif" st=
yle=3D"font-size:11pt" color=3D"#000000"><b>From:</b> Openexr-devel &lt;ope=
nexr-devel-bounces&#43;[email protected]&gt; on behalf of Pe=
ter Hillman &lt;[email protected]&gt;<br>
<b>Sent:</b> Monday, August 14, 2017 8:23:51 PM<br>
<b>Cc:</b> [email protected]<br>
<b>Subject:</b> [Openexr-devel] Proposal for storing ID manifests in OpenEX=
R headers</font>
<div>&nbsp;</div>
</div>
<div>Hi all,<br>
<br>
As Deke mentioned earlier, At Siggraph I presented a proposal for an OpenEX=
R attribute to store ID manifests (i.e. a table that maps between text stri=
ng names of entities and the numerical values encoded in the EXR image) Att=
ached is an updated draft giving
 more details of this proposal. There are a few modifications from the earl=
ier draft following suggestions from those attending Siggraph: many thanks =
to all those who commented.<br>
<br>
This is <i>not</i> a proposed complete single standard for storing IDs with=
in OpenEXRs. There are reasons to choose one storage scheme over another de=
pending on circumstances, suggesting that it is worthwhile to support diffe=
rent encoding schemes. The requirement
 for an ID manifest is a common requirement amongst those schemes. This doc=
ument merely defines a standard attribute for encoding the manifest and for=
 allowing it to be compressed. This should allow for a standard set of tool=
s for reading, writing and examining
 the attribute. <br>
<br>
The intention is that I will implement this attribute in the next few month=
s - certainly before the end of the year.&nbsp; Feel free to comment on the=
 standard before then!<br>
<br>
Peter<br>
<br>
<br>
</div>
</body>
</html>

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