Re: [Openexr-devel] Blender + OpenEXR

[Joseph Goldstone]

Hello Ton--

Your question is a deep one.  Some things that might help in making a  
recommendation:

(1) What do you mean by "'linear' RGB color space"?  Speaking  
informally, if you increase by a factor of two the number of red  
photons being emitted, what happens to the R in your RGB?  Does it  
double?

(2) Do you want the projected result to have a certain 'look'?  Are  
you trying to make your movie appear as if it was a real-world scene  
captured by an HD camera, and then selected by the director when s/he  
looked at an HD monitor?  Or are you trying to make it appear as if  
you shot a real-world scene on film, and you want the digital  
projection to look like a projected film print struck from an  
original camera negative?

(3) What's the ratio of the lightness of your brightest intended  
output color to that of your darkest intended output color?

(4) Cineon/DPX frames can contain either log-encoded density or gamma- 
encoded colorimetry.  Do you know which one the Quantel is set up to  
expect?  Do you know which type of the two the staff of the facility  
are more comfortable using?

You need to decide how you want the result to look, consider your  
current encoding (I think we are all hoping your OpenEXR file encodes  
colors in what we would call 'energy linear' where that R value did  
in fact double), and then examine the output pipeline to figure out  
how to go from what you have to what that output pipeline accepts.  I  
would be surprised indeed if your facility with the Quantel was set  
up to accept Cineon/DPX in 'energy linear' space, so you are going to  
have a bit of work to do.

best--
--joseph

ps: there's been a __lot__ of work that takes into account the ideas  
in Florian's paper, but no commercial system to my knowledge  
implements the proposed architecture.


On Mar 1, 2006, at 2:56 AM, Ton Roosendaal wrote:

> Hi Florian & everyone,
>
> Let me first say a big thanks for OpenEXR! It has proven to be very  
> reliable and versatile addition to Blender, and one of the crucial  
> success factors or the movie project I was working on during the  
> past 9 months.
>
> Check out the sneak-peek on http://orange.blender.org
>
> Apart from integrating openexr in our regular image in/out  
> pipeline, it now also is going to be used  in the core of the  
> render pipeline, taking care of saving tiles for all render-layers  
> and passes in a single file. This then in the end is handed over  
> the Blender built-in compositor to do the fancy tricks with. Docs  
> about this new pipeline and release is expected early april. It's  
> going to be quite nice, at least for the open source community. :)
>
> Our renderfarm (60+ dual cpu nodes), now is nicely spitting out the  
> exr files. Very shortly we have to convert all of that to the  
> format required by the HD digital projection in the cinema in  
> Amsterdam.
>
> My current information is that we have to convert this to Cineon or  
> DPX, this is moved to a Quantel IQ HD/2K set, which will convert  
> this to HDCam SR tape.
>
> This is actually my first real experience with HD digital cinema...  
> and I wondered if there ever was a follow up on the  
> OpenEXRColorManagement.pdf you published. All our frames are  
> rendered with a 'linear' RGB color space now, which look pretty  
> much OK on our monitors (like the 23" Apple Cinema displays), but  
> that doesn't mean anything eh. :)
>
> I would greatly appreciate some pointers to information or tips for  
> how to achieve the best quality for current 10 bits/component  
> digital HD projection systems. And maybe some hints for how to  
> convert color best to current DVD video formats.
>
> All the best,
>
> -Ton-
>
> (Resent this mail, it was sent february 25th, but nongnu.org  
> bounced it)
>
> ---------------------------------------------------------------------- 
> ----
> Ton Roosendaal  Blender Foundation address@hidden http:// 
> www.blender.org
>
>
>
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