OpenEXR

[ssalo]

The strange thing is that if I uncheck the "import/output 32 bpc format as linear light" the brightness seems being correct, but as far as I know this is not the right way to follow.

I always do that and no problems so far. Should I be worried.... ;)

-Sami

[Mylenium]

Hello!

I need some advices in order to composite some openEXR stuff. When import OpenEXR sequence, they looks too bright. I've already checked the Stu Maschwitz's tips&techinques and downloaded is linear color profiles but the thing seems not working. The strange thing is that if I uncheck the "import/output 32 bpc format as linear light" the brightness seems being correct, but as far as I know this is not the right way to follow.

Thank U in advance

PS the sequences are generated from 3DMax+Vray

Not sure, but this may be a problem in the way the Gamma is stored in the EXR from VRay/ MAX. Have you used one of the 32 bpc specific filters and see any significant change?

Mylenium

[DhAoS]

Not sure, but this may be a problem in the way the Gamma is stored in the EXR from VRay/ MAX. Have you used one of the 32 bpc specific filters and see any significant change?

Mylenium

Yes I can detect a little amount of smearing in the major highlights zone using box and gaussian blur (but also some 16bpc plugins seems doing the job). My doubts are generated from what I read in the Maschwitz blog: if you want to achieve a more photographic look you have to use a linear color workspace.
Maybe I'm too obsessed by this, but I'm a total noob for what concerning working with 32bpc.

[Mylenium]

Yes I can detect a little amount of smearing in the major highlights zone using box and gaussian blur (but also some 16bpc plugins seems doing the job). My doubts are generated from what I read in the Maschwitz blog: if you want to achieve a more photographic look you have to use a linear color workspace.
Maybe I'm too obsessed by this, but I'm a total noob for what concerning working with 32bpc.

Well, technically linear is only correct for dealing with film stock (which Stu does a lot, obviously) to simulate processes digitally and make the results look as if the were done by physical film-to-film operations. I'm not that much into 32bpc yet myself, but maybe Stu's linear profiles collide with what AE does to linearize data. I'd need to check that. I'm sure it's just a minor option somewhere that makes things go whacky.

Mylenium

[Vympel]

Well, technically linear is only correct for dealing with film stock (which Stu does a lot, obviously) to simulate processes digitally and make the results look as if the were done by physical film-to-film operations. I'm not that much into 32bpc yet myself, but maybe Stu's linear profiles collide with what AE does to linearize data. I'd need to check that. I'm sure it's just a minor option somewhere that makes things go whacky.

Mylenium

Probably the Stu uses this term (linear images) for other images like encoded sRGB (these images have a type of gamma correction) images not only for film.


Maybe the MAX or Vray insert some type of gamma correction in the images (theoretically the OpenEXR files is linear, without any type of correction) or the AE don´t recognize this type of file and apply automatically some type of color correction (color profiles, gammas adjusts...)

[payton]

Probably the Stu uses this term (linear images) for other images like encoded sRGB

there are people out there who will call this (sRGB) "linear", but stu definitely not.

payton

[Vympel]

there are people out there who will call this (sRGB) "linear", but stu definitely not.

payton

My Mistake! In the last post, my intention is to say that sRGB image isn´t a linear image (gamma encoded, etc). To linearize the image is need to use the correct color profiles or gamma operations like, inverse gamma

[payton]

maybe it was your fault. but there are really people that call gamma corrected footage (like sRGB) "linear". in the meantime they call it that way when comparing to "logarithmic" stuff like cineon.

because this thread is going to be a gamma-debate i will remind this one here (http://forums.cgsociety.org/showthread.php?t=386325&highlight=gamma+payton)

its a thread i started about gamma. but no one joined. maybe this time :)

payton

[beenyweenies]

Hello!

I need some advices in order to composite some openEXR stuff. When import OpenEXR sequence, they looks too bright. I've already checked the Stu Maschwitz's tips&techinques and downloaded is linear color profiles but the thing seems not working. The strange thing is that if I uncheck the "import/output 32 bpc format as linear light" the brightness seems being correct, but as far as I know this is not the right way to follow.

1. Did you remember to set your AE project to use the linear profile from Stu's site? Without that, all is lost. In your Project Settings, make sure that 32bpc is selected and the linear profile you got from Stu is selected in the "Working Space" dropdown.

If that doesn't fix it right off, try:

2. Select your footage item on the timeline and choose Effect>Utility>Color Profiles Converter (I think that's what it's called). Set the file's input profile type in the first box (in this case, linear), and choose "document work space" or whatever that option is for the output profile. This step may not be needed for Linear files, but the basic idea here is that AE assumes any file you import is in the same color space as your project is set to. Step 1 should have fixed this, but who knows.

Either way don't forget that when you go to render, you have to add another step in the mix if you want normal, viewable renders. Subcomp your main composition, and add an adjustment layer with the Color Profile Converter effect applied to it (yes, again.) This time, set the input to Linear and the output to sRGB. Everything will blow out, because you've just turned off your linear "correction" for viewing. Next step is to go to View menu, Proof Setup to Unmanaged and turn Proof Colors ON. I usually build out this render comp early on so whenever I need to render I just use it. You can also add in 16bit effects here if needed.

I am totally working from memory here so sorry if some of these names are off a bit, but this is the basic process for working linear and outputting the result to a useable file.

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