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Reversing the IPP2 Image transform LUTS? Possible?

Jason Tan

Jason Tan

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Hi,
Just in starting a project with a bunch of VFX. The VFX house wanted to try IPP2 - medium contrast, very soft highlight Tone map to use as their source footage.

So I'm getting footage back but I need to grade it with a bunch of different sources that are either Red Raw or some form of Log, like SonySLog. The footage coming back has that tone map baked in with super saturated and hefty contrast - is there way to undo that IPP2 LUT so that I can keep the whole timeline in a loggish way.

I have downloaded the IPP2 cube luts from Red, but they only seem to add the tone maps and not convert back to default IPP2.

Or is there some other method I'm missing?
 
Jason,

If the files haven't been transcoded from an .r3d file to something else, in Davinci Resolve, Press" Shift+9" and in the "Camera Raw" tab for "RED" use these settings below. They will revert all the .r3d files back to the "Log Like" "RedwidegamutRGB/Log3G10" flat image that you can use a different "IPP2 Tone Map and Highlight Roll-off with than what was captured. Also the red footage will come into the project already converted in a flat RWG/Log3g10 image. You can then in the raw tab in "color" page change the footage back to a "legacy" combination you may feel more comfortable with, like "Dragoncolor2/Redgamma4".


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[/url]Screenshot (158) by rand thompson, on Flickr[/IMG]


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[/url]Screenshot (269) by rand thompson, on Flickr[/IMG]


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[/url]Screenshot (77) by rand thompson, on Flickr[/IMG]
 
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Yes they already pulled their plates from the r3d files using the IPP2 - medium curve profile in Redcine-X and composited shots with them. The completed composites that are coming back are pretty tough to work with in that colour space. The colours are all over the place so it would be better go back to the default. I think what I need is a reverse .cube for those tone profiles. That should be possible no?
 
Jason,

So what are the file types of the footage you will be receiving back to work with?
 
It's Prores4444 with the same baked in Tone Curve and wide color gamut.
 
The VFX house messed up. They should have worked on RedLogFilm and previewed with a LUT, not baked the LUT in!

That said, It would be very handy if there were inverse LUTs provided by RED to get from a given IPP2 setup back into RedLogFilm, even if they weren't 100% perfect.

Bruce Allen
www.bruceallen.tv
 
Jason,


Since they are no longer .r3d files, the looks of those clips, as you stated, are pretty much "Baked in" and "IPP2" is completely useless now. Now you can only "counteract" the effects of how the VFX house processed them. If you want to post a frame, if you legally can, of a few prores files, I will see if there is anything I can do to help you if I can.
 
Yeah I think good ol redlogfilm would have been a better choice right now. Or if we see a reverse IPP2 LUT then we can do it that way too. I'm testing that right now.

Is there already a redlogfilm to rec709 LUT already out there somewhere for VFX work?
 
Thanks for testing Jason. If users have similar issues, please contact me directly.

Graeme
 
Jason Tan said:
The colours are all over the place so it would be better go back to the default. I think what I need is a reverse .cube for those tone profiles. That should be possible no?
Click to expand...

Fully - no.

To something more usable - yes.
 
Wouldn't Resolve's Colour Transform work for this? e.g. Keep the footage raw, apply Colour Transform with RWG/L3G10 as input and Rec709/BT1886 output, create a LUT and then use that LUT throughout the VFX workflow?

As for the currently baked/graded files, that's not IPP2's fault. It sounds like they did more than just MedCon/VerySoftRoll (since the footage is super contrasty/saturated)... *IF* that's all that's been applied, try using Colour Transform but with Rec709/BT1886 as input, and RWG/L3G10 as output. That'll get you log-ish, but definitely no longer accurate (meaning the colourist is going to have to do everything by eye moving forward... Which they likely would've had to do any way if there were a bunch of different cameras being used in their own log flavours.)
 
I sent Jason some prototype inverses which will more accurately get him back to the exact log starting point than the Resolve colour management could achieve. The problem with just inverting out the REC709/BT1886 is that the standard BT1886 has no concept of the highlight rolloff used, and thus the resulting log image will still be quite compressed. By my using of the correct highlight rolloff math, I can invert that out too and produce a much fuller range log image.

Graeme
 
Graeme Nattress said:
I sent Jason some prototype inverses which will more accurately get him back to the exact log starting point than the Resolve colour management could achieve. The problem with just inverting out the REC709/BT1886 is that the standard BT1886 has no concept of the highlight rolloff used, and thus the resulting log image will still be quite compressed. By my using of the correct highlight rolloff math, I can invert that out too and produce a much fuller range log image.

Graeme
Click to expand...

Want to try them very much yes. email me bjorn at syndicate dot se.
 
Would like to have redraw2linear and reverse lut and then linear2IPP2 and reverse lut any one made such luts?
 
so far i've only had one project as throughly screwed up as this one seems to be, and reverse engineering to a high standard the baked in decisions of a inexperenced person doing VFX is not a simple task at the best of times, alot of knob twiddeling....

there's so many permutations of the IPP2 workflow on offer that creating a ARRI style web page with drop down menu's could be of great value on a bad day... hopefully that bad day does not cross my doorstep anytime soon
 
Dermot Shane said:
so far i've only had one project as throughly screwed up as this one seems to be, and reverse engineering to a high standard the baked in decisions of a inexperenced person doing VFX is not a simple task at the best of times, alot of knob twiddeling....

there's so many permutations of the IPP2 workflow on offer that creating a ARRI style web page with drop down menu's could be of great value on a bad day... hopefully that bad day does not cross my doorstep anytime soon
Click to expand...

Thos drop-down menus are all in REDCine-X which will export the LUTs you'd need.

Graeme
 
Graeme Nattress said:
Thos drop-down menus are all in REDCine-X which will export the LUTs you'd need.

Graeme
Click to expand...
can baked in wacko decisions be reversed with REDCine-X? i could put in the paramiters applied to cam orignal plates when they were pulled, includeing DRX, DEB, rolloff etc and create a LUT or CDL that gets the plates back to a known standard in REDCine-X?

if so, good to have that in my back pocket, if another trainwreck like this one ever crosses my door, i'll send the person who did the deed to REDCine-X, make reverseing the process their issue, not mine....
 
REDCine-X makes the same kind of output LUTs that the mentioned ARRI LUT creator makes - only you don't need to go to a website - you just use the RED Tool you already have. The ARRI web site does not provide inverses.

For inverses, at the moment, you'll need to come to me, but we'll look at making them more available once they've been more thoroughly tested.

Graeme
 
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