AE & 10bit log DPX from .r3d - Color Issues

[photoreel]

Hi,

I'm in post on an indie film shot on the Red One that has lots of greenscreen work. I'm having some color issues working with the footage in AE. Here's what I'm doing:

I exported the 10-bit log DPX files from RedAlert using Camera RBG / Redlog settings (full debayer.)

In After Effects, I've been using Adobe's recommended color management workflow for DPX files, which is as follows:
In File>Project Settings, you choose Depth - 32-bit, Working Space - Universal Camera Film Printing Density, and check the "Linearize working space" box.
Then import the DPX sequence.
Right-click the footage and go to "interpret footage>Main". Under the Color Management tab choose Universal Camera Film Printing Density.
Click OK.
Create a new comp by dragging the DPX sequence onto the filmstrip icon.
Then click anywhere in your comp. Then go to View>Simulate Output and choose Universal Camera Film Printing Density. I'm also assuming that simulating the view for Rec.709 works, by selecting that.

This workflow has been giving me some strange results. Highlights will often times be clipped, even though they were definitely not overexposed during the shoot.

I was wondering if anyone might have figured out a better way to work with 10-bit log DPX files in AE (as I mentioned the DPX files were rendered with RedAlert using the CameraRGB/RedLog settings from the original .r3D file.)

Thanks,
Michael

 

[Uli Plank]

I'm not using DPX in AE, since I'm on CS5, which can work with native R3D.

But since you mention color issues and have been using REDAlert: if there was any recent firmware on the camera, that is wrong from the start!

 

[Charles Angus]

RedLog won't work with tools that are expecting standard Kodak Cineon log. RegLog compresses the image into a 0-1023 log curve, but normally log files exist in the 95-685 range.

Moral of the story: don't use RedLog. Use RedLogFilm (which is like a Cineon curve), or - as Uli Plank suggests - simply import the R3Ds natively, if you're working in AE.

 

[Robert Niessner]

Better use the new RedColor and RedGamma and render to OpenEXR files (those tend to be smaller than DPX). Import that into After Effects (in color management set interpret as linear light to OFF). Gives much better colors to start with.

If you do not want to re-render, try the following:
Check your highlights at the info panel - do they show values above 1.0? If yes nothing is clipped in the DPX, AE just renders it clipped to the display. Apply the filter HDR Compander (found under effects -> utilities) and raise the gain setting. This will map down your highlights below 1.0. Just raise the Gain enough to get the highlights back. Use Gamma to compensate for the darkened mid-tones.
You could create a new adjustment layer for just the HDR compander and put that above all other layers.

 

[Charles Angus]

Or, if you're brave, you can try interpreting your RedLog footage in AE by going to the color management tab in the interpret footage window, and futzing with the cineon settings.

Not recommended, but possible.

 

[photoreel]

Thanks for the suggestions everyone. I have tried adjusting the Cineon settings via "interpret footage" and gotten some good results, but sometimes the footage gets a little dark by doing this.

Because of issues like clipping highlights, or the footage becoming a little dark when trying to "correctly" color manage these 10-bit log DPX files created from the .r3Ds, I'm thinking of just re-exporting all of my shots as 16-bit linear TIFF files and redoing my vfx with those. Is there any disadvantage to working with 16-bit linear TIFF rather than 10-bit Log DPX files? I know that if you shoot on film 10-bit DPX files are a better choice, but since the Red is acquiring the image digitally do you really lose anything by exporting to 16-bit linear TIFF?

Thanks,
Michael

 

[Robert Niessner]

Michael, I would really recommend using the OpenEXR format. It will keep you in float land, keeping all the details in the highlights and it is using lossless compression to keep the data down. For me OpenEXR is far superior to DPX or 16-bit TIFF. Give it a try.

 

[Michael McNeff]

Hey Robert,

Thanks for your comments. Are OpenEXRs a log or linear format?

Best regards,
Michael

 

[Charles Angus]

EXR is linear. Log is (AFAIK) only used in DPX/Cineon.

The disadvantage to going to a higher bit-depth format is increased file size and I/O requirements - a 16-bit file is almost twice as big as a 10-bit file.

Oh, and photoreel - this is a real name forum. Please change your login to be your name (last initial is fine).

EDIT: Nevermind - I just realized that you seem to have re-registered with your real name.

Re-welcome aboard!

 

[Gunleik Groven]

I'd really give RedlogFilm/Recolor 2 a try both for exr/dpx
Linearises very well.
Haven't used this with AE, but it is like a dream come true with nuke...

 

[Robert Niessner]

Michael, I am quoting from Mark Christiansen's book "After Effects Professional Studio Techniques":

As much as Cineon log is a great way to encode light captured by film, it should not be used for compositing or other image transformations. This point is so important that it just has to be emphasized again:

Encoding color spaces are not compositing color spaces.

OpenEXR is a high dynamic-range (HDR) image file format developed by Industrial Light & Magic for use in computer imaging applications.

OpenEXR's features include:

• Higher dynamic range and color precision than existing 8- and 10-bit image file formats.
• Support for 16-bit floating-point, 32-bit floating-point, and 32-bit integer pixels. The 16-bit floating-point format, called "half", is compatible with the half data type in NVIDIA's Cg graphics language and is supported natively on their new GeForce FX and Quadro FX 3D graphics solutions.
• Multiple lossless image compression algorithms. Some of the included codecs can achieve 2:1 lossless compression ratios on images with film grain.

If being sent for film-out, use 10 bit log-encoded Cineon/DPX. This is also converted for you from 32 bpc linear, but be sure to choose the Working Space as the output profile and that in Cineon Settings, you use the Standard preset, which is a universal standard. Facilities around the world know what to do with it.