.r3d/Nuke workflow

alezan · **.r3d/Nuke workflow -** March 11th, 2010, 05:02 AM

Hi everybody!
I've searched the forum for this argument, but I didn't find something to clear me ideas once and for all. Forgive me if It's a stupid question...

I got to do a removal, involving some tracking in Mocha, for a shot taken with Red camera. The footage is in .r3d format, logaritmic, and the director ask me to keep this format because he will use it for color after the vfx.
I use Nuke for the compositing part. My questions are:
_what should be the correct workflow to import/work/render the scene in Nuke? (Read>log2lin>removal and color>lin2log>render?)
_what is the best way to manage log files and using LUT in Nuke?
_I can import .r3d file in Nuke, but I can't render it out: what is the better lossless format to use both to import and to write out the comp? (exr?) Is reasonable to use it directly or should I convert the footage in RED softwares like RedCine/RedRushes etc...?

I hope I haven't done too many questions. Thank you all in advance for the attention and, of course, for all the site that is really a "gold" mine of information...

Ale

Dezperados · March 11th, 2010, 05:16 AM

Hi.

r3d is a container format, you cannot work with it, it is way to slow.

The best thing is to convert to log dpx or cin and then work in Nuke and afterward, you re-convert to dpx or cin back.

r3d has, as far as I know, 12Bit Data. But working directly with these files is no option since it is lagging all the time. So if you convert to 10bit Log cineons or dpx, you get most of the 12bit r3d data out and you still have the wonderful overbrights and so on in Nuke.

In the r3d Nuke settings, there are some sliders for log curves and so on. This is the way to go.

Alternatively, you can convert the r3d files directly to dpx/cin via Redcine. I tried it once, it crahsed here, maybe you have better luck.

alezan · March 11th, 2010, 06:06 AM

Hi Dezperados! (good nick

... from the western film?)
Thank you for speed...
Yes, I tried to work with it but, as you said is slow.
I would try to not use dpx to avoid the bit cut out, if possible.
I found this post
http://www.reduser.net/forum/showthread.php?t=19692
and, as I can understand, they advice to export openEXR 16bit from Redcine, and then render the final in DPX.
I can't even found the format in Redcine export window (only DPX and tiff)... a mac version issue? (meanwhile I'm trying to use it to export DPX as you said, I hope it will not crash...)
Perhaps I can use Nuke to export in exr, and work with them.
what you think? could it be useful to preserve bits but maybe quite slow...

g2r · March 11th, 2010, 06:26 AM

I haven't worked before with r3d files. But the usual procedure with log files is as follows.
You first convert to lin space, work there, and then convert back to log using exactly the same parameters you used to linearize.
In nuke, if you set the colorspace knob of the read node to cineon, it already converts the image to linear for you.
In the same way, in the write file, if you set the colorspace knob to cineon, it does the inverse process for you.
So in a transparent way, you input and ouput log images, but always work in linear space.
Regarding the luts. You have to have a lut to convert from linear to your desired lab look, so you can work seeing your comp as it will be filmed. You plug that LUT into the viewer lut knob. That one is on sRGB by default.
In Nuke, the usual file format to use is exr, for many reasons: it supports layers, bounding box, float and half-float, compression, etc
So if you have to choose, EXR is a good choice.
Hope this helps a bit.

alezan · March 11th, 2010, 08:00 AM

thank you to g2r... it helps.
one question:
the retouching in photoshop, is better to do it on lin converted image or on the original log?
In the past I have requested to do on log original dpx files, but now I am not so sure we have done right...

g2r · March 11th, 2010, 08:26 AM

The mathematics of most tools are done in linear, and therefore it expects to be applied to linear images.
So I'd rather work over a linear conversion. Although remember that when you linearize, some values may get over the 1 limit, and therefore to avoid clamping important information you have to save the image in float. Only PS CS4 can handle that if I'm not wrong.
Though for cloning operations and a bit of painting it doesn't matter that you are in log space.
The problems begin when you color correct log images with linear mathematics!

So it all depends on what you're going to do, and the nature of your images.
Some of the retouching can be done in Nuke as well, maintaining the float space, without having to go to PS.

alezan · March 11th, 2010, 08:34 AM

thanks, it helps... more!

Rnode · March 14th, 2010, 01:21 AM

just a little addition...

.r3d RED-raw files are JPEG200, wavelet compressed (±1:12) files with a bayer pattern from the cmos.
Since the bayer pattern is red's little secret, debayering can only be done with their SDK, so writing
r3d codec is not possible.

The debayering is done on the fly in Nuke and is a CPU intensive process. Which is why these
files feel slow. Converting to another format as mentioned before, solves this.

It's not necessary at all to debayer to files with higher bitrate than 16 bit. There's just not enough data.
One thing you have to get right though is the gamma curve and colour space used in the camera while shooting.
You need to remove those in redcine/redalert to make it linair. The DOP can tell you those.

The rest has been suggested already here

alezan · 06:40 AM

Hi Rnode, thanks for the explanation.
Currently I am using Redcine-X to open the R3D and render out DPX files.
I have seen that there is a small button, upper right, that says "reset to metadata"... when I push It gave me RedSpace as Color Space and also as Gamma space. I hope this help to maintain the settings of the camera, is it right?
So I have done the follow:
imported R3d > push that botton > export DPX.
Would this be a correct workflow?
I also tried to manual modify and export as " REC709 for Color space and RedSpace for Gamma space", because it looks more correct. The first mode gave me files a bit washed out, they seem log.
They told me that they used RedSpace for monitoring while taking the shot, and they prefer the first version files, RedSpace RedSpace, so I am using these in Nuke, using this color space also in Read and Write nodes.

Another problem is that the exported DPX are 8 mb each and I don't know if they are really 16 bit.I can't found the bit settings window in Redcine and, as I said before, even not the EXR format in the export window (only DPX and tiff).

Sorry if I have made too much dumb questions...
but I would love to reach a real lossless workflow

Rnode · March 14th, 2010, 07:15 AM

you're welcome alezan

there are no dumb questions, only dumb answers. why would there be any forums at all if everyone was equally brilliant

linear images don't look correct, they look too dark cuz they have gamma 1 and not any monitor gamma around 2.2. you need to "undo" what the camera did with the images. it's probably in the metadata but i'd check with the operators to be sure.

dpx can be anything from 8 bit to 16 bit log or lin, even with up to 8 layers. usually though it's 10 bit log.
they could well be 8 MB per frame. do the math: height * width * 3 channels * bitdepth / 8 (n * 1024)...
there should be a setting to choose the bitdepth. not for all formats though...

rohitm · March 27th, 2010, 02:47 AM

use cameraRGB for decode color space

and rec709 for the gamma curve..
debayer = high
olpf well i keep it off but depending on the footage u may wanne keep it on medium.

redspace makes pics look amazing but results in loss of some color/luma info.

Quote:

Originally Posted by alezan

Hi Rnode, thanks for the explanation.
Currently I am using Redcine-X to open the R3D and render out DPX files.
I have seen that there is a small button, upper right, that says "reset to metadata"... when I push It gave me RedSpace as Color Space and also as Gamma space. I hope this help to maintain the settings of the camera, is it right?
So I have done the follow:
imported R3d > push that botton > export DPX.
Would this be a correct workflow?
I also tried to manual modify and export as " REC709 for Color space and RedSpace for Gamma space", because it looks more correct. The first mode gave me files a bit washed out, they seem log.
They told me that they used RedSpace for monitoring while taking the shot, and they prefer the first version files, RedSpace RedSpace, so I am using these in Nuke, using this color space also in Read and Write nodes.

Another problem is that the exported DPX are 8 mb each and I don't know if they are really 16 bit.I can't found the bit settings window in Redcine and, as I said before, even not the EXR format in the export window (only DPX and tiff).

Sorry if I have made too much dumb questions...
but I would love to reach a real lossless workflow