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Old September 23rd, 2007, 03:53 PM   #1
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After Effects Workflow

Hello,

I'm using cineform raw 2k files in after effects CS3 and I was wondering if there is a resource and/or guide for truly understanding the color correction/compositing workflow. Here are a few of the questions I'm looking for definitive answers on:
- What are the standard after effects settings one would use when working with cineform raw files in regards to- color depth, color profiles/workspace?

- Is there an option to disable the .look file associated with a clip and apply a new 3d LUT and color correction within after effects? I have been adjusting .looks via prospect 2k in premiere, but this does not give me the range of control I have in AFX.

... Right now I'm working in after effects with 8 bit depth, no color management & no way to turn off .look files (the more options button is disabled for some reason). I've noticed that when i output my comps to animation quicktimes there is a significant shift in gamma (much brighter). I have a feeling im doing something wrong, so if anyone has advice for me it is greatly appreciated!
Thanks,
Sean
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Old September 24th, 2007, 02:07 PM   #2
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If you want to disable the .look files youŽll have to use the Build 135 of Prospect 2K, because the new CFHIO importer in After Effects is not detecting the Codec properly. The only dissadvantage is that you wont be able to export Quicktime files with that release in AECS3.

If you want to grade your footage inside After Effects (maybe using Color Finesse) you dont need to export your footage to another format, you can do it directly on the RAW and the export to an apropriate format depending on your deliverable. Its always better to work in 16 or 32 bits because you can produce some banding in an 8bits colorspace, and if youŽre working in RAW maybe your source is a SI2K or a Wafian, so your footage has to be 10bit, so in 8bits you are loosing color information. If you work in 32float youŽll have to correct the gamma to 2.2, or add a Cineon converter filter to improve the dynamic range and set to standard LOG curve.

If your intention is to finish your project in a dedicated color correcting or finishing system iŽll recommend you to export your footage to DPX sequences, quicktimes files always have gamma shifts, that happens with all quicktime codecs, and is not a big problem, you only have to adjust the contrast when exporting to quicktime. (less brightness, more contrast).
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Old September 24th, 2007, 02:28 PM   #3
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Sorry, no, the last build works fine. The issue is the new CS3 API not seeming to support "more options", I have a question with Adobe on this and I'm waiting for an answer.

If you delete im-CFHD_File_Import.prm from C:\Program Files\Adobe\Common\Plug-ins\CS3\MediaCore, and remove the Adobe components from ImporterAVI.prm and ImporterDirectShow.prm from C:\Program Files\Adobe\Adobe After Effects CS3\Support Files\(Media Core plug-ins)\en_us, then everything works like AE7.0. Waiting for a solution from Adobe.
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Old September 24th, 2007, 02:31 PM   #4
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Sorry for the missunderstanding David, I will remove those from latest build then.

By the way your latest post in the Cineform blog is grat.

http://cineform.blogspot.com/
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Old September 24th, 2007, 03:40 PM   #5
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Thanks for the tips Sergio.
Is there anything more to grading within after effects than just applying filters to the footage? I notice that when i turn the .look file off & apply a color effect I am then just adjusting a low contrast, de-saturated image. If i boost saturation it does not look right. Is there a specific effect that needs to be applied (such as a 3d LUT) before I really dig into color correction?

Regarding the gamma shift in quicktime.. This is my first time working with the cineform raw codec & editing/compositing on a pc. Usually we work with Final Cut & AFX in OSX, exporting lots of quicktimes to the blackmagic uncompressed codec for effects work & never having issues with gamma shifts.
However that is not the workflow on this project...
I notice that if i bring the exported quicktimes (animation full res) back into after effects the gamma shifts back down and everything looks normal. Is there perhaps some setting within AFX that needs to be adjusted?

Thanks again for the help. I really appreciate it!!
-sean
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Old September 24th, 2007, 03:50 PM   #6
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Quote:
Originally Posted by Sean Hellfritsch View Post
Is there anything more to grading within after effects than just applying filters to the footage? I notice that when i turn the .look file off & apply a color effect I am then just adjusting a low contrast, de-saturated image. If i boost saturation it does not look right. Is there a specific effect that needs to be applied (such as a 3d LUT) before I really dig into color correction?
Everything is done with filters. When you turn the 3D .look processing off, you are getting a very RAW image with a lot of lattitude. This will require you to white balance and control the saturation use AE filters, before applying your creative look. Leaving the look on can simplify this base work, but it will depend on your project to which approach is more appropriate.
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Old September 24th, 2007, 03:51 PM   #7
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Quote:
Originally Posted by Sergio Sanchez View Post
Sorry for the missunderstanding David, I will remove those from latest build then.

By the way your latest post in the Cineform blog is grat.

http://cineform.blogspot.com/

Thank you. I would love more feedback on what types in information should go on the blog (maybe in a new thread.)
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Old September 25th, 2007, 01:57 AM   #8
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Quote:
Originally Posted by Sean Hellfritsch View Post
Thanks for the tips Sergio.
Is there anything more to grading within after effects than just applying filters to the footage? I notice that when i turn the .look file off & apply a color effect I am then just adjusting a low contrast, de-saturated image. If i boost saturation it does not look right. Is there a specific effect that needs to be applied (such as a 3d LUT) before I really dig into color correction?
When you turn off the .look metadata like that, you've also removed the matrix, or anything I've setup in the .look that is being used to properly calibrate the color-space of the camera. So when you apply a straight saturation, the color-vectors aren't aligned. I have a tutorial on using SpeedGrade OnSet where I go though the calibration routine for the camera. It's in the Workflows section of our website.

Now, that being said, you don't NEED SpeedGrade OnSet for camera calibration, this was just one place where you can pick-up the settings and see the workflow in-action.

Should you decide to forgo the color management that the CineForm codec can provide using .look files (side note: I understand that not being able to change .look files in AE kind-of hampers the effectiveness of the flexibility that the CineForm color-management pipeline can provide with 3D LUTs . . . but it's MUCH more flexible and in many cases more accurate than ICC profiles, especially profiles that are not based on simple matricies but more complicated 3D LUT's as the CineForm spec allows for more accurate 3D LUT's than the ICC spec), you will need to-do the following:

1) Turn off the .look metadata for the file. This can be done in Premiere Pro per-file, or alternatively you can delete the .look files out of the C:\Program Files\Common Files\CineForm\LUT's\ directory . . . that latter is the brute-force technique, I recommend using Premiere Pro to turn off the .look metadata if you need to-do this, but sometimes the brute-force technique is good if you have a lot of files.

2) Turn on 32-bit float mode so that you get a re-linearized representation of the RAW file. You should see the footage get very dark.

3) I'm assuming the footage has already been white-balanced. If it hasn't, apply white-balance.

4) Apply the proper matrix transformation using some form of channel-based operation:

R = 1.611*R + -0.48*G + -0.131*B
G = -0.313*R + 1.525*G + -.212*B
B = 0.037*R + -1.118*G + 2.08*B

The above of course would only work in a program like Shake, etc. that has a colorX or other math-exrpression-based channel operation.

For AE, you can use the Channel Mixer filter. Use the same weight (coefficient) values, only multiply them by 100.

5) Apply 2.2 gamma correction or apply a Cineon curve, or whatever type of gamma-correction you need for your pipeline, or just export EXR's.

Quote:
Regarding the gamma shift in quicktime.. This is my first time working with the cineform raw codec & editing/compositing on a pc. Usually we work with Final Cut & AFX in OSX, exporting lots of quicktimes to the blackmagic uncompressed codec for effects work & never having issues with gamma shifts.
However that is not the workflow on this project...
I notice that if i bring the exported quicktimes (animation full res) back into after effects the gamma shifts back down and everything looks normal. Is there perhaps some setting within AFX that needs to be adjusted?
No, this is stupid QT player on the PC or the QT engine in general . . . the fact that AE interprets the file correctly (i.e., a round-trip out and back into the program still has the correct gamma) means that the actual values in the file are fine, but the way they are being rendered by QT are going through some sort of color-management LUT or profile somewhere that is messing things up a bit. Also on Windows, QT player uses the video card overlay features, so if you have slightly different color-correction happening on your video card overlays, you'll see a shift as well.
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Old September 25th, 2007, 03:58 PM   #9
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Wow, Jason- thank you so much. That was exactly the kind of advice I have been looking for. I think that information (a guide to prepping footage for use in after effects) would make a great addition to the support sections of SI & Cineform's websites.
If you could provide me with more details on the specific effects you would use to prepare a comp in AFX (to set the white balance & gamma), and the settings for those effects/filters, I'd really appreciate it.
I guess I'm basically looking for a template.
Another thing I've noticed is that the channel mixer effect is one of the many filters not "officially" supported by AFX in 32bit float mode. Do you think this really matters in the end? What about 16bit? is 32bit overkill?
Once again, thanks for the insight- this helps a ton.
sincerely,
sean
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Old September 25th, 2007, 04:43 PM   #10
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Hey Jason:

I was looking the workflow clips you uploaded in the Silicon Imaging website, and I noticed that you were using a Kodak250Dprint.look applied to the footage, where did you get those LUT's?
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Old September 25th, 2007, 09:28 PM   #11
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Hi Sean,

For the gamma correction, use the middle tab in the Levels filter (so not the one on the white-and black point, but the one in the middle).

For white-balance, use the Levels again, and clip the signal to the highest R, G, and B values in 32-bit float mode (or to gain up the channels if they are already clipped to something that is white-balanced). Then use the white-output (the point on the farthest end to the right on the second gradient line below the histogram) to set the white-point back to a setting you want it at (in 32-bit float mode this will allow you to regain any head-room you might have clipped). Keep in mind that if the green-channel is clipped, when you go into float mode and get a linaer representation, you might get "magenta" highlights . . . this is from having a clipped green-channel and imbalanced red and blue channel. The way to get rid of it is to gain up the red and blue channel to match the gain on the green-channel, and again, you do that with the Levels filter.

Use 32-bit float mode as you MUST do these operations in linear space, and in 32-bit float, CineForm automatically re-linearizes the RAW file back to a linear-light representation.

It's not ideal that the channel mixer is not 32-bit float compatible . . . that sort of sucks, but it should be placed after the Levels which is being used for white-balance.

The Levels for gamma correction should be placed after the Channel Mixer, not before, nor should it be combined with the Levels for white-balance . . . as David suggested, for the gamma-correction Levels, I would use an adjustment layer on top of your footage.

Thanks,

Jason

P.S. Sergio, that series of .look files was created through careful statistical modeling of a scanned OCN of Kodak 250D.
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