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Red_Oddity
09-08-2004, 09:02 AM
Where do i adjust the LUT of my imported Cineon files inside LW...
A Cineon importer without the ability to adjust my LUT and see exactly what happens to the Log Linear / Linear Log conversion is pretty useless...is there a plugin i'm missing? Not even the manual even mentions this...

Thanks in advance

Lightwolf
09-08-2004, 09:35 AM
Where do i adjust the LUT of my imported Cineon files inside LW...

I haven't found anything yet either... I juust log-lin them in DF and sumpe them out as SGI 64 bit... better than nothing I guess ;)

Cheers,
Mike

Mr Rid
03-24-2008, 04:09 PM
I am running into a big problem with this. Am having to light CG elements to match DPX images with no way to see the images correctly in LW. I have to continuously save out single frame renders as EXRs (from the floating point Image Viewer) and compare them in AE to the corrected footage. What's more is I have to turn the gamma down on all color texture maps in LW. This makes CG meshes appear dark in LW but correct in AE. Messy.

gerardstrada
04-06-2008, 06:47 PM
Apply a Cineon Coverter in a compositing package and save it as an EXR.



Gerardo

Red_Oddity
04-07-2008, 05:11 AM
I am running into a big problem with this. Am having to light CG elements to match DPX images with no way to see the images correctly in LW. I have to continuously save out single frame renders as EXRs (from the floating point Image Viewer) and compare them in AE to the corrected footage. What's more is I have to turn the gamma down on all color texture maps in LW. This makes CG meshes appear dark in LW but correct in AE. Messy.

I have a workaround for this, so you can work in a linear workflow while making previews with a corrected gamma.

http://www.newtek.com/forums/showpost.php?p=648314&postcount=4

The node network can be used as a template to create more complex color space conversions aswell.

gerardstrada
04-07-2008, 12:07 PM
I have a workaround for this, so you can work in a linear workflow while making previews with a corrected gamma.

http://www.newtek.com/forums/showpost.php?p=648314&postcount=4

The node network can be used as a template to create more complex color space conversions aswell.

You may want to take a look at this (http://www.newtek.com/forums/showthread.php?p=683725)



Gerardo

Mr Rid
05-05-2008, 11:09 PM
Am applying the free CC Tools plugin- http://www2.informatik.hu-berlin.de/~goetsch/CCTools/ to fake a display LUT in the Image Filter. Haven't quite figured out the best pipeline. Compositors are applying a display LUT in After Effects that adjusts the live plates to appear as they will look on film. But EXRs out of 3D appear washed out under the same LUT in the comp. Am trying to compensate with the faux LUT in LW but it still makes the task of lighting difficult.

gerardstrada
05-06-2008, 08:25 PM
I shared a cineon/DPX pipeline in Issues #18 and #19 of HDRI3D magazine :) But concept is very simple:

Basically, forget cineon converters (they can be very inaccurate), it's better if compositors assign the proper negative film profile directly to the cineon file as LUT and bake it in a EXR by choosing the working color space of the whole project as output profile.

Then CG artists can load these files without converting anything in pre-process. They just can use a color management similar to the one I shared in lightwiki tutorial (the motion picture production setup).

Cheers,



Gerardo

Mr Rid
05-07-2008, 01:07 AM
Not sure if I understand. But 2D cant bake the LUT.

It's like if you pretend the LUT amounts to throwing say a red light over the plate to make it appear as it should on film. So if they give me a plate with a red light baked over it, and I then throw a red light over my CG to match, then when they bring the 3D into the comp where the red light is being applied as a display LUT again... the CG now has twice the red.

In AE, the linear EXRs have to be interpreted differently than the plates do, so then the LUT affects them differently. I cant get my brain around it.

gerardstrada
05-07-2008, 05:33 AM
If the compositor has assigned the negative film profile to the Cineon file and has saved this footage (EXR) with the working color space profile as output profile, he/she don't need to re-assign any other color profile than the working color space when the EXR file is loaded again (it has the negative film already baked in it). Of course, he/she can proof colors for let's say previewing how the output sequence will look like in a specific cinema theater. This color management workflow assumes that the whole team is using the same working color space for the entire project (in every phase and app). That's one of the advantages of SG_CCTools, we can work directly in the master working color space, we don't need a connection space for CG work anymore :thumbsup:

Thus, if a CG artist loads these EXR files in LW, it's assumed that he/she has setup the SG_CCTools in such a way it works properly in the chosen working color space for the given project so that they can have an approximation about how will look in the negative film printing density or even how will look this result in a specific cinema theater (just the same as the compositing package). Just remember the LUT setup with SG_CCFilter is only for preview purposes. When CG artists finish their work, before to set up the master_scene, they disable the SG_CCFilter in post-processing, so that the output render be in concordance with the working color space (assuming the working color space is a device-independent color space - if the working color space is a negative film color space, other workflow is obviously needed).

Later, when post-productor loads these rendered sequences in the compositing package, the working color space should be assigned for them.



Gerardo

P.D. You should really read those articles in HDRI3D magazine :)

Mr Rid
05-07-2008, 01:29 PM
I have only skimmed the HDRI articles but the supervisors I am working with have been over it, as well as several other articles, and discussed wth a number of very knowledgeble people. Still have not figured out a pipeline that works correctly. This stuff is complicated to convey in text. Every answer that I read spawns five new questions.

At the moment, when I use CC Tools to apply the appropriate temp LUT in LW, it is distorting levels and colors so much that it requires greatly exaggerated compensation of values for lights and textures to get things looking even close to what they should. For instance, with a simple grey ball with 200% spec and a 500% key I only get milky grey highlights under the LUT. The LUT is correct because the plate looks correct when rendered as a backgrond in LW. But it is just too weird trying to get the CG to look right.

I am not sure why not just light to a version of the plate before the LUT.

gerardstrada
05-07-2008, 08:32 PM
Because CG artists would be working below the limited color space of their LDR monitors. It can be surely converted later to a higher color space (which is what we made when we used a connection space), but we are not taking real profit of the color richness of wider color spaces and the incidence that this has in CGI in terms of realistic lighting&shading; besides, for compensating this, DI process gets more complex, and commonly, together with this, we don't realize that we are not taking advantage of real light intensities values.

And this has a lot to do with the exaggerated compensation of values for lights and surfaces that you were talking previously; but please, do notice that's not a compensation. That is to say, working within a color management workflow in CG - within the 3D package - requires to work with real contrast ratios of light (and linear workflows of course).

In CG, when we work without a color management facility, we are working in fact within our monitor color space. That means that we adjust perceptually all our colors and lighting values to about 8EVs (lights at 100% only). Consider that advanced film stocks can catch about 10EVs (in logarithmic space) or up to 13EVs (in linear space), which implies about 1000-8000 % of light intensity - I'm not taking into account the increment in nominal distance of inverse square falloff which can diminish these values depending on the distance - I'm talking about values measured directly in FP images. Now, consider real light contrast ratios are A LOT more higher than that, and this is evident when we have captured the lighting in location (through a lightprobe) to reconstruct it later in CG - HDRI HandBook from Blochi might really help to understand easily these concepts.

Most of people adjust the HDR lighting intensity to make the preview image pleasant, but they don't consider that they are working in FP space and the LDR nature of their monitors deceives their perception. If we are really working with a FP pipeline is to take profit of it later. So a better strategy is to compress or tone map the preview result with post-filters - temporarily - instead of diminishing the real dynamic range of the scene (about a nodal tone mapping solution within LW, you might want to take a look at this thread (http://www.newtek.com/forums/showthread.php?t=83604)). One or other is obviously in dependence on the dynamic range level chosen for a given project.

In the DI process, we can take profit of this dynamic range, not only for color grading but for the digital answer print (for approvals) and during the film out process.

A color management workflow wouldn't have been possible without a FP pipeline, it's really needed to begin to take profit of it. Consider as well that these workflows allow us to have a very near approximation about how our work will finally look at a very early stage of the production by simplifying and speeding the DI process up (and hopefully reducing the costs).



Gerardo

Mr Rid
05-08-2008, 05:12 PM
The problem is that using a display LUT is introducing a great deal more complication, when the 'old' pipeline worked just fine. Talking to artists from RnH, Sony, Domain, and Cafe, they are all lighting to color corrected plates.

I am not sure what is wrong with just baking the LUT into the plate, lighting to that, then 2D can comp using the CC plate and the 3D elements matched to the CC plate, then they can back out or reverse the CC before saving.

But for example, I lit a grey ball with a highlight and soft shadow falloff the normal way. But I can not begin to get the same lighting under the display LUT no matter what I make the lights. Highlights remain milky, and I dont have control.

Lightwolf
05-08-2008, 06:00 PM
Display LUTs are usually from log to the display (assuming this is for film), omitting the step of converting into actual linear colour space (which is where all processing - compositing or rendering - ought to be done ideally). That might be the issue.

Cheers,
Mike

gerardstrada
05-08-2008, 08:07 PM
David,

I realize we weren't talking about the same things from the beginning. The workflow proposed in the article is precisely to color correct plates after lighting, since we are working with a wider color space - ProPhoto RGB in that case- not a negative film space. Working with a color space like ProphotoRGB is advisable since it's a device-independent color space. Then, below this workflow, we convert from ProPhoto(lin) to our monitor color space (log) - just like the lightwiki tutorial. In this case, the LUT is our monitor color space, since our working color space is ProPhotoRGB. I thought you were talking about this when you said LUT. But it seems you were referring to "LUT" for a negative film or theatre preview profile. The LUT setup proposed in the article and lightwiki tutorial is to compose (within the limited LW compositing capabilities) a Cineon file with a rendered sequence worked in ProphotoRGB as working color space with a negative print LUT. Now, as far as I understand, you want to integrate (not compose) CG elements with cineon footage in the same frame. For that, we need other workflow (that I haven't shared it in those articles because the purpose was to provide an overview about the general usage for several output mediums).

In that specific case, we have to approximate the negative film 'look' within LW for both, cineon footage and CG elements, at the same time. As you can figure out, the setup for the negative film is pretty simple and you can be sure we can get nice results in lighting with the negative film LUT applied. Below this workflow, happens the contrary of what you mentioned before, if you are accustomed to adjust the exposure by tweaking lights intensities, you'd need to diminish lights intensities since we get contrasted results - just like a common film 'look'.

I've been seeing this workflow with some studios privately, but I'll update the lightwiki tutorial with this info to avoid confusions.

Cheers,



Gerardo

Red_Oddity
05-09-2008, 02:50 AM
Nice to see this thread still going, still learning alot from all you guys around...btw...we just back ordered those HDRI 3d magazines (and took a year subscription just for the heck of it, seems like a nice magazine)

Also, Blochi's forums (atleast, i asume HDRlabs is Christian Bloch's site) have more people running around with linear workflow experience (HDRLabs.com)

Also, Laffrey's Fusion mailing list has a lot of knowledgable people running around (ILM compositors included)