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Old January 13th, 2009, 10:02 AM   #1
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fixing results of auto exposure in vegas

I have some clips that get lighter and darker as the camera moves up and not, mainly because the auto exposure wasn't turned off on my camera when filming. Is there a plugin that will help to balance this out?

Or is there a way to successfully improve it using keyframes. I would be conerned that using brightness/contrast and then trying to tweak with keyframes would simply make it worse, but I thought there might be a plugin out there that could recognize when the video gets brighter, and darken it down a bit.
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Old January 13th, 2009, 10:59 AM   #2
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I usually use the Levels FX to get make adjustments to exposure. If things are really bad I lightly tweak the gain in the Color Correction FX.
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Old January 13th, 2009, 11:11 AM   #3
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but are you using keyframes to do this? my specific problem is that on some clips, I forgot to lock the exposure on my camera, iee someone walks by in front of the camera, and the frame gets brighter for a view seconds, then darker again. I need to somewhere to get rid of this little spots where the brightness changes.
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Old January 13th, 2009, 11:24 AM   #4
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Yes, keyframes would be the way to do this. If you're not that familiar with them yet, you're going to be *very* experienced pretty quick.

Take the exposure correction plug of your choice and drop it on the track.

Turn on "sync cursor", lower left of the window. Now, when you drag the cursor in the keyframes window around, you'll also be moving the cursor in your project. Arrange the windows so you can see the preview screen, and scopes would be a good idea too - display the waveform monitor.

Now you're ready to drop some keyframes. The trick is this: You want a keyframe at the beginning of an exposure change, you want another at the end of the exposure change. So, if someone walks in front of the camera, you probably want 4 keyframes - 1 to begin, a second to hold at the new setting, a third to start the return to the old setting, and a 4th that is the old setting.

****edit - here is a step-by-step****
(in this example, let's assume that some one walks in front and the iris of the camera opened to compensate, overexposing the background image)
a) Insert a keyframe (using the buttons at the bottom) #1 at the beginning of the exposure change - there is no exposure change for this one.
b) Advance to where the background is brightest (maximum exposure change) and adjust the plugin's settings to the picture you want. With sync cursor turned on, this will automatically drop a new keyframe (#2).
c) Advance to the end of the too-bright section, and, again using the insert keyframe button, drop another (#3). This should still have the same settings as keyframe 2.
d) Advance to the desired end of the effect, where the camera exposure has returned to normal, and adjust the plugin settings back to zero, thus dropping keyframe #4. You're done with that section.
***end edit***

Notice that the settings of keyframes 1 and 4, and 2 and 3 are identical. Yes, you can copy and paste keyframes.

This is one of those things that's harder to write about than to do, but keyframes are kinda' tricky until you get the underlying logic.

Once you've got some facility with laying down 4 keyframes for your exposure errors, check out Vegas help for some info on keyframe behaviors - these can be accessed by right-clicking on a keyframe.

Also see volume 2 number 8 of Edward Troxel's excellent newsletters.

Last edited by Seth Bloombaum; January 13th, 2009 at 11:40 AM. Reason: added step-by-step instructions
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Old January 13th, 2009, 11:37 AM   #5
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awesome that helps alot thanks
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Old January 13th, 2009, 04:59 PM   #6
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Hi Jay,

Just as Seth said, key frames works great. The procedure he outlined is the one I use. I also use the Waveform video scope to monitor the changes in luminance. It makes it really easy to see where the exposure starts to change and when I've gotten it to match the previous keyframe.

Garrett
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Old January 14th, 2009, 03:06 AM   #7
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You could try splitting the event at the point where the exposure changes, alter the levels on the new event and then crossfade it with the original event to smooth out the difference.
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Old January 14th, 2009, 03:30 AM   #8
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Tony's method is quick and dirty and works for many incidents such as you've describe. I've used it many times.
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Old June 1st, 2011, 03:19 PM   #9
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Re: fixing results of auto exposure in vegas

So, is there a plugin to do this automatically or more easily? Say, fix the exposure of a single frame and tell the plugin to adjust TO this exposure for the rest.
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Old June 1st, 2011, 03:57 PM   #10
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Re: fixing results of auto exposure in vegas

Mike Crash has two filters (Auto Levels and Levels Correction) on his site that may be of some help to you.
You have nothing to lose but some time experimenting with them.

Mike Crash Vegas filters
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Old June 1st, 2011, 05:33 PM   #11
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Re: fixing results of auto exposure in vegas

Mike Crash has some great stuff but I don't think he's supported it for a while and I'm not sure it works past version 7 or 8. But it's worth a try.
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Old June 1st, 2011, 06:15 PM   #12
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Re: fixing results of auto exposure in vegas

Don, they still work in 32-bit Pro 10 for me.
AFAIK, 64-bit has never been supported.
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