[Sidefx-houdini-list] unpremultiplied rendering?

Peter Bowmar pbowmar at gmail.com
Mon Jul 19 12:37:01 EDT 2010


The problem is, it's extra unneeded processing.

Any time a compositor wants to colour correct something, they do it on
unpremultiplied imagery, then mult by alpha  afterwards. So, really,
the renderer should put out unpremultiplied if possible to avoid extra
processing. IMO :)

Cheers,

Peter B

On 19 July 2010 08:51, Andrew D Lyons <tstexture at gmail.com> wrote:
> I would agree the shader is the wrong place to do it. Similarly - I'm not
> convinced that the ROP option would be much better.
>
> The COP option is the best IMHO. Taunt them that the Houdini compositor can
> handle it and their compositor can't, and see how fast they decide they can
> do it. ;)
>
> Cheers
>
>
> On 19 July 2010 08:44, katrin schmid <Katisss at gmx.de> wrote:
>
>> hi,
>> while this is possible i dont intend
>> to hard code it into the shaders.
>> Hm, even an option in the shader seems the wrong place really.
>> We are looking for the option but i do think
>> we want a choice. I try the Cop and see what its used for.
>> Thanks for your help,
>> katrin
>>
>>
>> -------- Original-Nachricht --------
>> > Datum: Mon, 19 Jul 2010 08:38:30 -0700
>> > Von: Andrew D Lyons <tstexture at gmail.com>
>> > An: sidefx-houdini-list at sidefx.com
>> > Betreff: Re: [Sidefx-houdini-list] unpremultiplied rendering?
>>
>> > If you have access to your shader code you could divide your color output
>> > by
>> > your alpha prior to output. That should do it.
>> >
>> > On 18 July 2010 22:53, katrin schmid <Katisss at gmx.de> wrote:
>> >
>> > > hi,
>> > > i have been asked to unpremultiply passes post render.
>> > > Which sort of lets me wonder if we i couldnt render this way in first
>> > > place.
>> > > Anybody know how to do this?
>> > > Best Regards,
>> > > katrin
>> > >
>> > > --
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>> >
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>> > Andrew D Lyons | Digital Artist | http://www.tstex.com
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>
>
>
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> Andrew D Lyons | Digital Artist | http://www.tstex.com
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