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Old May 16th, 2006, 02:18 PM   #1
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Color correction question

I am using Color Finesse with P-Pro-2 for color correction. I also purchased and have struggled with the book "Color Correction for Digital Video".

So far the following simple technique has helped make my video color look better. Keep in mind.. the goal is to gain all around better color and resolution.

Using the RGB-WFM in Color Finesse I use the RGB curves to manipulate each of the three RGB "clouds" on the WFM. I lower each of the highlights to 90 IRE and push each of the three colors (RGB) shadows up to 7.5 IRE. That alone typically improves the picture quality. I then stretch the levels using the curves so that I match (more or less) the shape of all three RGB. Occasionally I stretch the mids on each color.

In the end I end up with three identical looking color clouds on the RGB-WFM. The overall picture (9 out of 10 times) looks better.

Am I approaching this correctly?
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Old May 16th, 2006, 04:16 PM   #2
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In my opinion... it's better if you make the levels peg the maximum legal white and black levels.

2- There's no such thing as IRE in the digital realm. This can make things confusing when you want to figure out the right digital black and white levels.

Color Finesse can only measure DIGITAL levels. For it to show analog levels (i.e. IRE), it can only guess. So that's a little bit confusing.

3- I don't think you should match the shape of the RGB clouds... that'll cause color shifts which you may not want.

4- IMO, the best things you can do are (in order of importance):
For video-originated footage, things will usually look better if you add contrast and a touch of saturation. Treat the flesh tones seperately so they look normal after increasing saturation.

If the piece if narrative, you could kind of use color like music and "score" your entire piece. Play with tints, contrast, saturation, and diffusion/glow effects to create looks.

Use vignettes or masks to draw attention to certain areas, or bring detail out in particular areas.
i.e. in after effects, unsharp mask inside a mask on actor's eyes
use adjustment layers + motion tracking + masking + levels to raise/lower exposure in certain areas. (Like power windows on a da vinci, except better.)
Detailed corrections like these suck up the most time and are the least noticeable. Sometimes it may not make sense to bother doing this.

5- There's really no "correct" approach. I'd do whatever looks better (and better is a subjective thing).
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Old May 16th, 2006, 06:38 PM   #3
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Glen-

Thank you for the quick and detailed response.

I have some footage that was shot with an XL2. The camera was white balanced in one room (kids birthday party). When the camera was used in another room with (yellowish lighting) everything looks.... well.... yellow.

I'm looking for a way to clean out the yellowish tint using Color Finesse. Like I said, I was using the RGB-WFM with curves to do this. Here is an example of one frame that I fixed using my method.

I certinaly am going about it wrong.... Any additional tips would be appreciated.

Thanks again!
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Old May 16th, 2006, 06:42 PM   #4
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Well... I thought I attached the two frames... I'll have to figure out how to attach them.



Sorry
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File Type: zip Color_Correction_Examples.zip (413.0 KB, 102 views)
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Old May 16th, 2006, 06:58 PM   #5
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Here is another example. I used the vectorscope and the master hue offset to move the "cloud" more to the center. Part of it (in the red area) was off the outer circle.
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File Type: zip Color_Correction_Examples_using_hue_offset.zip (405.7 KB, 91 views)
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Old May 17th, 2006, 11:44 AM   #6
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There should be three big color wheels in CF... the one on the right controls white balance. You should be able to play with that to get rid of the cast.

You might also need to use the middle wheel... I can't remember.

That's what the wheels are for anyways.
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Old May 17th, 2006, 12:41 PM   #7
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Tim,

I don't believe getting all the clouds to match is the right approach. Every image is going to have varying contents that will shift things one way or another depending on the scene. It's not necessarily a bad thing.

To correct for improper white balance (and even "proper" white balance is sometimes off), you need to find a neutral reference point in the image, something gray/white/black. You need to use curves, etc. to get this reference to a true gray, equal values of R, G, and B.

It helps to shoot a reference chart at the head of each shot to help with color correction later on. The chart will have neutral values, a range of them, to help you correct the color balance, contrast, and exposure.

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Old May 17th, 2006, 05:24 PM   #8
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Thank you again!

I appreciate the feedback. I will try these suggestions. Color correction seems a bit intimidating to me...

Thanks again!

Tim
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