[Sidefx-houdini-list] Image File Formats

[Simon Barrick]

We work entirely in 8 bit and I find that .sgi is a remarkably portable
format and compresses better than .tga. 
There are plugins for photoshop to read .sgi and after effects can
handle it, plus many other packages.

Tiff is handy for importing into photoshop if you want proper decent
transparency, this is because Houdini correctly saves an "associated"
alpha in the true technical use of the word assiocated. Photoshop then
treats the alpha as transparent correctly just as it does with its own
native format. Sgi format just loads up with a black background and an
extra channel, so you then have to remove the background manually using
the alpha channel.


-----Original Message-----
From: John Coldrick [mailto:jc at axyzfx.com] 
Sent: 07 March 2006 14:10
To: sidefx-houdini-list at sidefx.com
Subject: Re: [Sidefx-houdini-list] Image File Formats


On Monday 06 March 2006 22:08, Johnson, Dave (Space Technology) wrote:
> I don't mean for this to be a religious debate about formats, I 
> realize there are different formats for many reasons--I'm just 
> interested in WHY you use what you use.

	I don't think there's any liklihood of religious format wars
here - too many 
level-headed people.  :P

	It's a tough one - I'll admit that as a smaller shop, we tend
not to have 
strictly controlled formats, and most people use whatever they want.
This 
inevitably makes for having to regurgitate at the last minute in another

format, so I guess it's evolution at work.  :)

	For us, the advantages and disadvantages:

	OExr - my personal fav, since I like to mock up(or actually
complete) 
compositing and I want the depth and headroom without as much weight as
full 
float.  Disadvantages: Larger image and our Discreet systems can't use 
them(yet).  As a personal workflow, I'll typically render in OExr, and 
precomp layers and spit out to 8 or 16 integer for the comp systems...

	...Tiff - the ol' warhorse.  Good thing - handles a wide range
of flavours, 
many packages support it.  Bad thing - the format has fragmented 
significantly and we've had trouble with some other systems, especially
Mac 
based applications, supporting it.  Sometimes, changing the compression
to 
none will help, sometimes not, depending on the app.  It's a pain
regardless 
- often forget to turn compression off, chaos ensues.

	tga - not bad if you're only sticking to 8 bit integer.  Rarely
use it myself 
*unless* it's going to a Mac, in which case it seems to be a no-headache

solution.  Unfortunately, our Discreet systems take *forever* to import
tga - 
it's a problem their end - so it's a hassle for us.

	Cineon - haven't gone this route yet - so far if we're working
in film we've 
worked in linear space our end with OExr, and converted if need be.  
Compositing in log space has it's own hassles, so typically it's used
here as 
an input/output path, although your needs may vary.

	SESI pic/rat - works great if you're doing an all-Houdini job, a
hassle 
otherwise for obvious reasons.


	What a pain!  :(  In my little fantasy world, everyone will
adopt OExr and it 
will become the de-facto standard, but I'm not holding my breath.  Until
it's 
adopted by worlds that still think in 8 bit(like video editing), it's
success 
will be limited IMHO.  No standard is perfect - tiff is wonderful, but 
corporate haggling over ownership has caused a problem.

	Cheers,

	J.C.

-- 

John Coldrick                  www.axyzfx.com        Axyz Animation
416-504-0425                                         425 Adelaide St W
                                                     Toronto, ON Canada
jc at axyzfx.com                                        M5V 1S4
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