Color Calibrating Live Action Footage?

[scrimski]

To avoid this toning in shoting you normally make a balance to white(?) or a "Weißabgleich" which means filming an object with no chroma information(usually a sheet of white or gray paper) in order to have an unsaturated reference point.

I would try to look for an colorwise neutral object in you scene, get it's color values with the eyedroppertool and to read out the values for hue and saturation.
Apply a coloring layer or operator on your 3d renderings which uses these hue and saturation values.

I prefer a balance to white in post for the footage though, bringing all footage and renderings to the same toning level and colorize them later, usually in Avid Xpress or AfterEffects.

[danylyon]

Thanks for the fast response.
No I'm not just talking about white balance (At least I don't think that's all to it).

To illustrate what I mean, look at the this two pictures. http://www.danybittel.ch/temp/dreh.jpg

The Top one is the HDRI shoot with a Canon.
The Bottom one is the Actual Live Acton Footage, shoot on 35 mm

If you compare, there are a lot of color and contrast differences. Obviously CCD's and Film Footage reacts totally different to light.

Now I'm wondering how to get the HDRI into a physical correct Colorspace, if it's not already there.
Then, if I light stuff with the HDRI in a 3D Software. How to get this 3D elements correctly tonemapped to the 35mm footage, so that it matches.

Normally I'd do this "by eye", I'm just wondering if it would help to shoot some Greyscale / Color Graphs and do the matching like that.

[scrimski]

as steated before, use a spot that ought to be grey and read out the Hue and Saturation difference.

In this particular case I would try to match the lightness(or darkness of the shadows) and then the red tone of the walls.
If you light up with an HDRI shouldn't be the lighting toned anyway by the HDRI?

[Pancho]

just realized that we are looking for the same thing. Yes, I'm sick of trying to match my stuff in a general way by my eye, compare it, pull a view triggers till I'm satified. I want to shoot two references and compare them with a program which takes care to match them. Your problem is a bit more complicated, as the mirrored ball is blurrying the image and reduces the contrast. But at least you should be able to compare two equal images, one from the 35mm and one from the D-SLR. There should be a way.

Cheers
Pancho

[danylyon]

I had some time today and digged around a little, still haven't found THE solution, but getting closer.

There are a few issues that need to be adressed first (I think).

1. Proper color calibrated Monitors, with something like Huey or Eye-One Display 2 (that's the one I ordered today =)
This will calibrate the colors of the monitor to a GAMMA 2.2 (PC).
(on second thought, actually, that isn't even 100% necessary, but still good)

2. Then I need to work in linear color space. So that none of my images have any built in Gamma correction for the screen. Which basicall means, all my images will be too dark, but a 50% gray will be a RGB (128/128/128) Pixel. This ensures that all the image manipulations happens in a proper manner. Like for example if I layer images they will act more "naturally". (You can read into it at the page I'm about to give).

3. Film has yet another Colorspace, examples can be seen here: http://www.aim-dtp.net/aim/technology/sensitometry/index.htm
(The website http://www.aim-dtp.net/ is a very good read on the topic.)
That mean's I'll need to find out the Colorresponse Curve of the Filmstock I'm using and adjust my 3D Footage acordingly. Or in other terms, Gamma Correct the 3D Footage for Film (instead of 2.2 for a PC screen)

do I make sense?

Now, how to get the "color response" Curve from Filmstock.
If I'm not totally mistaken, HDR Shop can do that... maybe even Photoshop CS2
I'll have to investigate more...

Edit: It's Gamma 2.2 for PC

[BadG3r]

So Im not quite sure if I cn help here.

Maybe you are looking for SENSITOMETRIC CURVES.
"The curves describe this film's response to red, green, and blue light. Sensitometric curves determine the change in density on the film for a given change in log exposure."

see pic: Looks to me for what youre looking for.


If you know on what stock you shot, then, I think, you can go to the firms website. There should be all the info you need.


Hope it helps.

igor

[beaker]

Sounds like your trying to do all your color matching in 3d when in reality you should be doing it in 2d. Just render a bunch of render layer passes and CC them in post to match. Thats why many companies have moved to a single job of Lighter/Compositor so they can control their images out of 3d and into 2d and use the best balance of work needed in both areas.

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