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dpx pipeline in ae

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Aoife Greenham
dpx pipeline in ae
on Apr 21, 2010 at 9:14:50 am

Posted this a few days ago with no responses, i'd really appreciate getting a response on this! thanks!

Hi there,

I'm an animation compositor, and am working on my first foray into a live-action animation mix. I want to ensure that i don't degrade the beautiful 2k footage i'm working on, while ensuring that the effects and animation i am creating in after effects are reproduced correctly. I have just been given the caveat that my client wants to colour correct the footage, SEPARATE to the effects I'm putting on. Their budget is low, and they couldn't afford a pre-effects and a post effects grade.
I'm using a lot of transfer modes in my effects, and i'd be real grateful if someone could take a look at my pipeline, and double check i have everything ok. I feel like I may be over-complicating, and am nervous of the log-lin aspects of this.

So here goes.

Import .dpx footage into ae.
32 bits per channel float
Colour workspace linear srgb iec61966-2.1 (D65)

Apply cineon converter, log-lin and bring highlight rolloff down to 0, as recommended by Pete O'Connell on this website (can't find it now)
apply exposure effect, bring down exposure by eye. Without this my footage is still too washed out for some reason.

Create effects, (to simulate overblown light leaks and film scratches) using transfer modes etc.

I'm stuck here.

If the client wants to grade the footage separately, I don't need to actually render the live-action footage, I'm just using it as reference. So all i need to render is my effects.

I render out each layer, using the naming convention of scenename_layerorder_transfermode. The grader can then re-build the scene as I intended it to look, with the ability to grade each layer as he sees fit.

The grader says he wants my effects as a dpx sequence. As far as i can see, i don't have the option to export dpxs from after effects, is it ok to render out cineons? Also, do i have to put a lin-log on my effects to render out? I'm assuming not, but just in case.

Sorry about the length of this, but want to be sure i'm clear, and want to get rid of any redundant steps i may have built in.

Thanks for your time,

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Chris Wright
Re: dpx pipeline in ae
on Apr 21, 2010 at 4:57:22 pm

AE is assuming that the imported footage is already in the Project Working Space. It's not. It's gamma-encoded, so it looks too bright. You have to manually convert the gamma-encoded colors in the image to the linear Project Working Space with color profile converter.

I know a lot of people get confused about this, much less messing with monitors calibrated. Here's an example aep from cs3, that is a full round trip loglin. I turned off the last 2 effects so you can see how to work in lin. Once you are done with the effects, apply the last 2 effects and render out. It's already setup for linear d65 plus monitor calibrated for HD. You know its done right when you can turn on all the effects then off, and the viewer remains the same. Finally, output a cineon dpx full range. Good Luck, and read these sites.

ae cs3 example log-lin
Log-Lin sites

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Chris Wright
Re: dpx pipeline in ae
on Apr 21, 2010 at 7:39:12 pm

"Create effects, (to simulate overblown light leaks and film scratches"

This free template has scratches, jitter, dirt, vignette, hair, light leaks, dust, exposure, flicker, etc. Just copy and paste or import the layers you would like to use, but remember to resize them as needed.

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Aoife Greenham
Re: dpx pipeline in ae
on Apr 22, 2010 at 9:27:57 am

Hey Chris,

thanks for that, i'll have a play with your old film effects, and really thanks a million for the advice on the colour profile converter.

Am i correct in saying that if i only render out my effects layers as .cin/.dpx, I can keep the same colour profile comp as the one i'm using, but can discard the log lin effects.

I'm just using the dpx footage as a reference for myself, and so I do need to know what the true colour levels are, but all i'm rendering out for the grader is the effects layers, which he will join with the original dpx footage.

I guess my question is: If rendering out various layers, jpegs, pngs etc, as dpx, do i need to convert them to log or lin space before rendering?

Thanks again, those links were brilliant.

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Chris Wright
Re: dpx pipeline in ae
on Apr 22, 2010 at 7:15:18 pm

You only use the color profile converter if you are using color management. It works with simulate output(given that you want to use a calibrated monitor and work perfectly with Photoshop). Either both are used, or neither.

All dpx are 10 bit log. They only temporarily go to linear so you can color correct. Everything else that is is not initially a log, needs to be converted to log also.

If you want furthur reading, I highly recommend that you delve into Adobe's white paper on color management.

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Chris Wright
Re: dpx pipeline in ae
on Apr 22, 2010 at 8:15:11 pm

To clarify, this color profile converter step is for dpx's only, not jpg's etc. because AE doesn't recognize the embedded profiles of gamma encoded dpx's. But you do want to enable scene referred if you have CS4 for jpg's.

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