On set colour correction

renfield sonia · February 10, 2011

Hi, I'm shooting a feature film on Viper camera. As it's supposed to be a sort of fake documentary that takes place before spanish civil war we're using lots of LUTs as a way of previsualizing the final colour results, and to correct the green cast of the viper camera. I'm using an iridas speedgrade software to create luts and using them on a cinetal monitor. The problem comes when we import the footage into final cut, I don't know how to import those luts onto the system so the method I use i quite poor as I create 3 way colour correction presets and by adding them to the timeline the director will have the option of watching the offline with a proper colour.

Does anyone knows a way to keep the onset colour timing process from monitoring to final cut timeline?

Phil Rhodes · February 10, 2011

I think there's an FCP plugin capable of 3D LUTs distributed with Glue Tools, but I've never used it.

There's also something for After Effects in CS5.

If you have consistent look throughout you can put it in the monitoring.

In Premiere you could nest a set of clips and apply a correction to those - I presume there's something similar in Final Cut.

What exactly is your situation - do you have, for instance, a sequence of clips that need to use one particular LUT, followed by another edited sequence which needs to use another? What are the differences between them - something you could simulate with FCP effects?

I think usually people would render the offline files with the LUT baked into them, but if you're creating a DVCPRO-HD camera original I assume you're viewing that directly.

P

renfield sonia · February 14, 2011

I'll check out the final cut plugin, it would be awesome to have the possibility to run monitor LUTs into the system and to provide a properly precorrected offline.

About your quesion we're using different LUTs throughout the project as there are at least two different looks for the movie, the fake documentary scenes (black and white) and the fake interviews (the dp wanted to create a colour correction imitating what would have been the colour in 1930 if those interviews had been shot... nice concept!

The LUTs are just created for monitoring purposes and we record the image in a RAW-Like mode, which brings out greenish footage, my concern is to colour correct those images so the director can cut the material without having to make any mind exercice to be in the correct mood. My colour presets are just very raw corrections to imitate the LUTs previously created and also correcting the differences of the footage (due to lughting conditions and so). When I've used other recording devices such as stwo OB1, the idea is to provide the offline with the exact LUts created on set.

Phil Rhodes · February 14, 2011

Have you verified that you're going to be happy with the sort of compression artifacts you'll get from shooting filmstream onto such a compressed format as DVCPRO-HD? I suspect it may work out OK, but I'd want to have tested it carefully first.

Bear in mind that any 3D LUT is going to be a real performance suck even if you can ifnd a way to put it on an NLE timeline.

My reaction to this situation would probably be to take the DVHD originals and run them through some software to create offlines with the LUTs baked in. There are approaches to doing this which can be done for not much money on a desktop PC, depending on exactly what corrections you want. Describing exactly how to do this is beyond what I can do in a forum thread but it is possible.

Otherwise, if you just want to take the Filmstream green out of it and somewhat normalize the contrast, you could just get something like a Blackmagic HDlink and put a LUT in the monitoring, if you don't have a Cinetal for the editor. That won't be per-clip, though, it'll be an overall correction.

P

renfield sonia · February 14, 2011

Hi Phil, I may haven't explained our workflow properly, the compression codec we're using isn't dvcpro HD even if we're using P2 cards, we're compressing in AVCINTRA 100, which is 10 bit 422 HD stream, up to now I've been told that this is the best way to record a 422 video stream. The video that comes out of the viper, using the HDSTREAM mode matches (it's the filmstream like raw curve but in 422) our recording system, I haven't noticed any compression artifacts, just some strong noise in the low end of the curve when the lut's been applied... noise that doesn't seem so noticeable without the LUT...

I'v tried the HD LINK system for monitoring purposes but it proved to be a pain in the ass for heavy shootings with many locations (the image and the connections end by failing). About using the HD link for edition displaying, I haven't thought about that... but I guess that it will take me the same amount of time to create colour presets for the FC than recreating the same luts for the cinema display. Anyway, about LUTs monitoring, I found out that they create lots of noise that added to the cinetal's own noise they can be a problem mainly in underexposed scenes... hope the colorist will find our original footage more useable...