I've now reviewed RFC 4288, *Media Type Specifications and Registration Procedures* (current best practices) with an eye to registering Radiance .pic/.hdr files as an internet type. I've avoided looking at other file types, at least for the moment. Here's some of my notes on this:
1. Since 2005, only a standards body can register an unqualified type; image/hdr, say. So we'd probably best come in as a "vendor" (broadly construed) type; image/vnd.radiance, perhaps. (I can make a case for vnd.radiance.hdr, but it seems like overkill).
2. We're encouraged (but not required) to submit information about the format of our files. I think it would be a good idea to submit the Radiance picture file format, possibly lightly edited and expanded. I'll sign up for the [email protected] mailing list and see what we might submit.
3. We need to conduct a security analysis, though I don't think we have major issues here. The main one is that .pic format does use compression, which might be used in a resource-denial attack.
...to be continued...
Randolph
···
On Oct 25, 2008, at 2:51 PM, R Fritz wrote:
It looks pretty straightforward; I'll have to review the submission requirements in more detail, but I don't see serious problems. We'll probably have to come in as an organization-specific type ("image/vnd.radiance"), since an unqualified type now has to come from a recognized standards body. I'll get back with more details later this week.
Randolph
On Oct 25, 2008, at 11:33 AM, Axel Jacobs wrote:
Randolph,
The official mime types are assined by the IANA:
http://www.iana.org/assignments/media-types/Getting .hdr accepted by IANA would mean that eventually all other
mime assignment, e.g.
for the various LINUX desktops:
http://standards.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-latest.html
will pick it upI started a thread here:
http://luminance.londonmet.ac.uk/radiance_mailinglists/dev/2006-November/000761.html
but it didn't lead anywhere.When I said I was not sufficiently confident about the file format,
then this is what I meant:
(see http://radsite.lbl.gov/radiance/refer/filefmts.pdf)HDR comes in two flavours:
- RGBE
- XYZEEach of those two flavours has three sub-flavours:
- non-rle
- rle
- mixedGreg (http://luminance.londonmet.ac.uk/radiance_mailinglists/dev/2006-November/000766.html):
-----------8<--------------Both, RGBE and XYZE come in flat and in RLE flavours. However, the
official file specs only mention two FORMAT= string, i.e. 32-
bit_rle_rgbe
and 32-bit_rle_xyze. How does this work?I decided not to sub-type based on the presence or absence of run-
length encoding. Since the reader routines identify RLE on a per
scanline basis (and in fact there can be a mix of RLE and
uncompressed scanlines), there seemed no need for a separate format
specifier.The MIME specs have the notion of subclasses. So would RGBE and
XYZE be
subclasses of RADIANCE HDR?Again, I wouldn't bother to distinguish these within MIME. It would
be like distinguishing between different classes of TIFF. Any
software that opens an RGBE file will also open an XYZE file, even if
it won't display the colors correctly.
-----------8<--------------So there you go...
I've started working on a mime XML file following the freedesktop.org
style. This is to make my yearly chore of rolling LEARNIX somewhat
easier. It's not well tested yet, but here is the first draft. The bit
with the extensions seems to work, but I haven't tried yet what
happens when the extension is removed (mime magick).Ignore all non-HDR stuff. I just thought I might as well leave it in,
in the hope of getting some comments.<?xml version="1.0" encoding="UTF-8"?>
<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info"><mime-type type="image/x-hdr">
<comment xml:lang="en">HDR image</comment>
<alias type="image/x-radiance"/>
<alias type="image/x-rgbe"/>
<magic priority="50">
<match type="string" value="#?RADIANCE" offset="0"/>
<match type="string" value="FORMAT=32-bit_rle_rgbe" offset="0:500"/>
</magic>
<glob pattern="*.hdr"/>
<glob pattern="*.unf"/>
<glob pattern="*.xyze"/>
<glob pattern="*.rgbe"/>
</mime-type><mime-type type="model/x-radiance-control">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance input</comment>
<glob pattern="*.rif"/>
</mime-type><mime-type type="application/x-radiance-octree">
<comment xml:lang="en">Radiance octree</comment>
<magic priority="50">
<match type="string" value="#?RADIANCE" offset="0"/>
<match type="string" value="FORMAT=Radiance_octree" offset="0:500"/>
</magic>
<glob pattern="*.oct"/>
</mime-type><mime-type type="application/x-radiance-ambient-cache">
<comment xml:lang="en">Radiance ambient cache</comment>
<glob pattern="*.amb"/>
</mime-type><mime-type type="model/x-radiance-holodeck-control">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance holodeck input</comment>
<glob pattern="*.hif"/>
</mime-type><mime-type type="application/x-radiance-holodeck">
<comment xml:lang="en">Radiance holodeck</comment>
<glob pattern="*.hdk"/>
</mime-type><mime-type type="model/x-radiance-geometry">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance geometry</comment>
<glob pattern="*.rad"/>
<glob pattern="*.norm"/>
</mime-type><mime-type type="model/x-radiance-triangle-mesh">
<comment xml:lang="en">Radiance triangle mesh</comment>
<glob pattern="*.rtm"/>
</mime-type><mime-type type="model/x-radiance-material">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance material</comment>
<glob pattern="*.mat"/>
</mime-type><mime-type type="model/x-radiance-view">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance view</comment>
<glob pattern="*.vf"/>
</mime-type><mime-type type="model/x-radiance-cal">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance cal</comment>
<glob pattern="*.cal"/>
</mime-type><mime-type type="model/x-radiance-bgraph">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance bgraph</comment>
<glob pattern="*.bgraph"/>
</mime-type><mime-type type="model/x-radiance-options">
<sub-class-of type="text/plain"/>
<comment xml:lang="en">Radiance options</comment>
<glob pattern="*.opt"/>
</mime-type></mime-info>
Axel
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