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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Redalert to DPX... Please explain?

Jason Wingrove

Jason Wingrove

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Can someone take me through what exactly converting from RedCine/Alert to DPX actually doesn't do to the original R3D information?
It seems you start with the full info of the R3D file then you make (somewhat retrograde) decisions before entering a grading suite by choosing ISO, REC 709 etc that affect the DPX and therefore limit what's available to you in the grade?

But if you find you need more range in the highs or lows for a particular shot you have to then exit your grade and re export a new DPX to try and get more information in a blown out window or see more into a murky shadow?

So have I got it wrong and I needn't worry as all the information on the R3D files goes through to the DPX and i'll want for nothing in dynamic range or colour space when i comes to grade or...

I'm right and Cine/Alert seem a restrictive step that by its nature surely MUST discard some information before you know you need it?

If so, how soon till established DI grading systems read R3D files natively? Baselight, Davinci resolve etc ...
so all you need to grade will be the relevant R3D files, an EDL and a guy with an eye?
 
The problem is that DI software doesn't know and doesn't have the tools to "develop" a RAW image. RedAlert and Redcine do.

So, currently:

use redlog, rec709 video gamma or PDlog,
set the white balance,
adjust exposure until no clipping (try -0.4EV to start)
neutralize out all the other controls.

Then you're not loosing anything in your DPX export.

Graeme
 
right, thanks graeme,
The issue im trying to get my head around is that if you do change exposure / iso etc in redcine to get detail in a blown out window you're compromising the shadow detail no? i

its the difference in grading neg vs tape to tape i guess? a DPX simply doesnt have the same depth of information as the original R3D in a pro grading environment?
 
Just be careful - if you set ISO to 320, -0.4EV is your starting point and you should not need to go beyond -1.0EV to make sure everything is in the data. The 10bit DPX, as long a you're not exporting linear light, has enough precision in the shadows still at that point, especially if you use REDLOG.

Graeme
 
Overall it would be much better if RED released the codec to Baselight etc so they can start making this stuff native?? How much easier would it be if we could just give the grader the DPX and an EDL? cmon RED help us all out in workflow dept
 
It's more complex than that though....

Graeme
 
I was thinking complex code, and infrastructure, and making things work right....

Graeme
 
undesstand, thanks graeme
just that there seems to be companies out there desperately waiting to "incorporate the Red codec the moment Red release it" and aren't being hampered by any technological issues! People working in a $2000 an hour grading suite don't want to fanny around with Redcine or popping out to tweak things and re-export dpx's

If they're serious about this camera being something more than an tool for low budget indy films then what's the holdup?.
 
Think Adobe has a team of 10 guys just to deal with DLSR raw formats, and that in reality we're talking very complex image generation, not how packed a bit is.
 
I've got a question about the specs for REDLOG , I understand to use PDlog685 in Shake or Color rBlack is 95, rWhite is 685, rNGamma is .6 & rDGamma is something like 1.7. Does anyone know the equivalent settings for using REDLOG in Shake or Color and also what the gamma settings for PDLog 985 might be.
 
Jashunter said:
well from what I understand companies out there directly involved are desperately waiting to "incorporate the Red codec the moment Red release it" and aren't being hampered by any technological issues! People working in a $2000 an hour grading suite don't want to fanny around with Redcine or popping in and out to tweak things and re-export dpx's If you're serious about this camera being something more than an tool for low budget indy films then what's the holdup?.
Click to expand...

Jas,

If you check the credits for the recently released "Jumper," you'll see quite a few RED-associated credits in that movie. I think a US$85 million feature with a box office of over US$100 million is probably a few steps above "low budget indy film." That film was graded at EFilm... on fairly well established grading systems.

"The Argentine," "Guerrilla" - Stephen Soderbergh. Also far above the "low budget indy film" level.

On none of these movies is there any popping in and out of Redcine or RED Alert to tweak things, because the post-production teams know what they are doing and are confident of the workflows involved.

Peter Jackson and Stephen Soderbergh have not released any work shot on Viper, Genesis, or Dalsa. David Fincher has shot extensively with Viper. Brian Singer with Genesis. Neither of them have shot with RED. Does that mean any of them are right or wrong?

What exactly is your complaint?

Lucas
-----
ASSIMILATE, Inc.
LA, CA, USA
 
Yes, i haven't done any $85m feature on RED, just a few TVC's
perhaps you've misunderstood me, I dont think i said anyone is wrong for shooting on genesis only (ive used it on several projects myself and its quite seemless to grade going direct from the original cam tapes just like neg) notquite sure of the point there.

My observation (please tell me if its flawed as this is all about me and others getting better educated along the way luke) is that going from redcine to DPX by nature (however slight) is a compromise given that you must make some grading decisions and adjustments before you go into the real grade?

Just that most places here use grading systems that obviously cant yet read the R3D files natively and im just wondering that wouldn't it be great to have all the depth of information in those files accesible in the grade just like grading right off the neg like we're used to.

Or did all those feature just hit Rec709, exported DPX's and go grade? never having to go back to R3D files to tweak things, they got it right everytime? ...or was scratch their answer?
 
Jashunter said:
... My observation (please tell me if its flawed as this is all about me and others getting better educated along the way luke) is that going from redcine to DPX by nature surely (however slight) is a compromise given that you must make some grading decisions before you go into the real grade.
Click to expand...

Let me pose the question a bit differently...

If you know what you are doing, can you get the best digital representation of a film frame with proper scanning? I believe so.

Think of the Redcine process as a RED teleCINE. You do not have to make grading decsisions. But you do have to make processing decisions. For instance, using the Color tools in REDCINE to evenly balance a shot, then rendering it out through the REDLog LUT preserves maximum range and flexibility in the shot. In my opinion, that is no more of a grading decision than deciding to transfer 35mm as flat and neutrally as possible to 10bit DPX. Perhaps I'm drawing too fine a semantic point between "grading" and "processing," but you get my point.

Jashunter said:
Just that most places here use grading systems that obviously cant read the R3D files natively and im just wondering that wouldn't it be great to have all the depth of information in those files accesible in the grade just like grading right off the neg like we're used to.
Click to expand...

Unless you are using a Hazeltine and chemicals, you are never grading right off the neg. You are grading off a well-scanned digital representation of film frames. So... it's either Neg -> Datacine -> DPX with film or RED -> Redcine -> DPX with RED. Either way, it's all about making proper choices during the conversion process to maximize range and choices during the DI.

Jashunter said:
Or did all those feature just hit Rec709, exported DPX's and grade from there?, never having to go back to R3D files to tweak things, they got it right everytime? ...or was scratch the answer?
Click to expand...

In some cases, SCRATCH is the answer. But certainly not in all. Several facilities are using SCRATCH as a conversion and conform tool on the way to other systems for DI. Several facilities don't have (or need) SCRATCH and are using REDCINE and/or RED Alert in conjunction with their DI system of choice to create successful workflows.

Best,

Lucas
------
ASSIMILATE, Inc.
LA, CA, USA
 
All makes sense Lucas thanks!
I guess it would still be great to have this step eliminated by integrating it into the final grading process given that its also a real time tunnel.

So you use RED log LUT? is there any FAQ or guideline thread or area for DPX exporting as this still seems a bit like alchemy even for people who know what they're doing?
 
Jas, from my observations so far and observing the histograms on a lot of test footage, I tend to think of it like film scanning.
You have a neg (.r3d files) that you have to turn into a digital image that another (non-native) app can use. In scanning you take a neg and place the d-min (unexposed area) at 95cv in 10bit log. This is a process that is done by the operator at setup.
I think of Redcine the same way, you (the operator) need to set black at about the right spot, but its more about retaining the highlight info and not clipping, therefore you adjust down the exposure (or ISO) to avoid clipping, making sure you don't take it so far that you start clipping blacks, although thats probably slightly less evil than clipping highlights.
A Redlog output of this (10 bit log dpx) gives you all the data you need to work with in the next app.
Flick between an output 10 bit dpx (via Redlog) file in say Xnview and the same .R3d file in Redcine.... see any difference?? (nope) 1:1 transfer, and you don't need calibration on your monitor to see this ( I like to check it both with and without a viewing LUT)
Its NOT the same with either of the PDlog settings. It does change your original data range so less is available.
 
There's no way you can clip black with -ve exposure adjustment, but you could reduce it's precision too much. Linear light 12bit to 10bit does just that - reduces it's precision way too much giving posterized shadows. That's why we say, if you want LL export, don't use a 10bit DPX.

Graeme
 
Graeme Nattress said:
There's no way you can clip black with -ve exposure adjustment, but you could reduce it's precision too much. Linear light 12bit to 10bit does just that - reduces it's precision way too much giving posterized shadows. That's why we say, if you want LL export, don't use a 10bit DPX.

Graeme
Click to expand...

Whould you be so kind as telling us mortals, at what setting to export to, then?:sarcasm:

Emmanuel
 
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