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-   -   What's the best way to correct footage from 2 different cameras so they match? (https://www.dvinfo.net/forum/open-dv-discussion/474037-whats-best-way-correct-footage-2-different-cameras-so-they-match.html)

Paul Cascio March 3rd, 2010 08:43 AM

What's the best way to correct footage from 2 different cameras so they match?
 
I hope I phrased that accurately.

If I do a two camera shoot two different cameras, let's say an EX1 and a 7D, what procedure/sequence would you use in your NLE's Color Correction function to try to get the colors to match so the footage appears to be shot with the same camera?

James Workman March 3rd, 2010 08:52 PM

Well, in lieu of some scientific method, or complex math problem, trial and error seems to work best for me. I use PPro CS3, and frequently mix footage from a small Panasonic consumer cam with my Sony HDR-FX7. I can get pretty close with the limited manual settings on the Panny, but it always requires a little color correction in post to look right.
I have found one of the easiest fixes is gamma correction. And, it helps me to put both clips side by side, go completely black on both, and then adjust up from there.

Marty Welk March 3rd, 2010 09:20 PM

first of course would be trying to match before having shot the first second of footage.
even if i had to twist the "paintable" camera into a mess, i would want to walk out with 2 cams that BEGAN as matched as possible.

scope first for the luma levels, get those matched up with the waveform monitor, get the black level (aka Setup) set, and the total luma ranges matching. just because you can SEE those things on a scope. scope, monitor, monitor, scope, back and forth using the visable lines of the scope with the visable picture trying to get both a machine level and a human eye viewing levels that match.

for the color ,i dont know, I am 99.8% of the time matched before , and when i have had to deal with multicam non-pro color nightmares, i did what i could, and just got it out. i mean they didnt care to begin with , and think thier unmatched footage is great, and didnt notice , so they wont notice that i only got it close anyway.

let me take that one unhappy step further, you will NEVER get a single chip camera of one manufature color to match in ALL places all colors to a 3-chip RGB camera from a different manufacture without some major miracle, or nobody would be using/paying for 3 chip cameras to get all the colors completly right.
The far ends of the spectrum thing will always be bent if not broken doing tricks to get a single imager to freq out the colors the same.
If you can SEE it , it will be because there is a lot of colors going on in the video, and you have enough saturation in the viewing. if you dont SEE it, then they wont, so who cares. if you got a black tux groom and a white dress bride in a white and wood colored church, and a grey city, your not going to see it. if you got a technicolor nightmare dress at an outdoor indian wedding, you will see it.

if somehow you SHOT a color chart, not some generated color bars , because generated color bars are NOT going through the lens or using the imager are they? if you shot a color chart with both cameras in the light they were used in, the way they were set, then fire up the Vectorscope , and dream on :-) no mater how many little adjustment things they give you them little lines will never land on top of eachother , but ya get close and ya go on.

YUV color adjustements SEEM to be a lot harder than RGB ones, when you just cant pull it off in YUV fire up the RGB color corrector and see if you can get it going there instead.

David W. Jones March 4th, 2010 07:27 AM

As mentioned shoot a chart off the top of each scene.

Reed Hewitt March 4th, 2010 08:27 AM

I'll agree, shoot a chart first thing. Also white balance on location rather than using the preset tungsten or daylight (in my experience, different consumer cameras have different opinions about these presets).

Once you're in post, there are a couple of things you can do. I use the levels filter to adjust gamma and then crunch the blacks and highlights of the better camera to match the limited range of the lesser camera. One trick that helps with color in your NLE is to subtly skew the color balance of both cameras in the same direction, i.e., with a warming filter. It gives both sets of footage more of a common thread and you can always pass it off as a stylistic choice. Heck, if you're going to play the "style" card, just convert it all to black and white. : )

One other thing you can do when you're shooting: try to frame your shots with each camera as differently as possible. If you're cutting between a very wide shot and a very close-up shot, the differences in color will not be as noticeable.

Ron Little March 4th, 2010 09:03 AM

How do you crunch the blacks and highlights? What tools do you use? Can you give me a short lesson on how to do that?

Reed Hewitt March 4th, 2010 09:44 AM

Crunching Blacks and Highlights: A Short Lesson :D
 
Sure, it's pretty straight forward. I'll try to explain it in terms of Premiere and FCP (I'm an FCP guy), but keep in mind that a lot of different filters can achieve similar results. These are just the easiest ways I know of.

In Premiere, there is a Levels filter in the Adjust folder. Just slap it on your clip and start playing with the "(RGB) Black Input Level", the "(RGB) White Input Level", and the "(RGB) Gamma". Raise the black input to crush the blacks, lower the white input to crush/clip the highlights, and adjust the gamma to lighten or darken the image as a whole.

In FCP, the Levels filter is very limited, so I use the level controls in the Color Corrector filter instead. In this case, you'll want to lower the blacks and raise the highlights to achieve the same results.

Keep in mind that what you are actually doing is cutting off the luminosity information at the top and bottom and stretching out the values in the middle to compensate. You are losing information, which explains why things get ugly when you push it too far, especially for those of us working in highly compressed formats like DV and HDV.

Crushing the blacks also increases the apparent saturation, which could be a good thing or a bad thing. Just watch out for it.

Even when I'm not trying to match two different cameras, I usually crush the blacks a little in the final color correction. This gives the footage nice touch of contrast and generally makes it look more filmic.

Ron Little March 4th, 2010 10:27 AM

Thank you that is very helpful.
Would you not use the contrast filter?

Reed Hewitt March 4th, 2010 02:05 PM

You certainly could use the contrast filter; it's essentially doing the same thing. I think the levels filter gives you a little more control, but it may not be necessary in most cases.

Maybe I just like all the extra little numbers and sliders in the levels filter. "There's more options so it must be better, right?"

Ron Little March 4th, 2010 08:08 PM

Thanks again. I will play around with that.

Paul Cascio March 5th, 2010 06:39 AM

Marty, Reed and everyone, thanks for a lot of great info. I will never again shoot multi-camera without including a gray scale chart and color bar chart in my initial shots.


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