White Balancing During a Color Change

[ This article was first published in the April, 2008, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]

Chris Skinner writes:

Is there a technique to white balance in this situation.

 

Going from outside to inside; This is a steady-cam clip:

 

1. Camera, with on camera 50w light (white balanced to natural light) is approaching door.
2. Door opens and tungsten light makes everything yellow as camera now goes into the interior.

I would like to adjust the white balance in a way that does not have the sharp change from exterior white balance to interior white balance.

 

The alternative I think is to “razor,” making two clips, and use a dip-to-color transition. However, I would loose the entire “continuous look” I was trying to use.

Larry replies: Chris, you can’t re-white-balance while shooting.

But you can change color correction settings during editing so that a clip changes color to account for the shift in light – by using keyframes in the color correction filter.

To do so:

• Apply the Color Correction 3-way filter to the clip in question.
• Double-click the clip to load it into the Viewer and click the Color Corrector 3-way tab at the top of the Viewer window.
• Color correct the first portion of your clip so it looks the way you want.
• When the transition to other color light starts, click the open diamond Ins/Del keyframe button to set a starting keyframe.

• Go to the end of the transition to the differently colored light and set a second keyframe. Without moving your playhead, adjust your colors until things look normal.

Now, as you move from one color light to another, the color corrector filter will compensate for the difference, keeping everything looking normal.

Here’s an article that explains a simple way to color correct, if this filter is new to you.

UPDATE – April 8, 2008

Shaun Roemich, of Gearhead Visual, sent in the following update:

Actually, you can change white balance while shooting if your camera has 2 manual white balance positions (A & B) on an external switch, such as most pro shoulder cams along with many of the newer HDV cameras have. Simply set white balance on B, go outside (in this example), white balance normally, go back inside and set white balance to A, white balance normally. Begin shooting outdoors and as you approach the threshold, simply flick the WB switch from A to B and Voilá! Some cameras even allow you set set the transistion between the two white balance values to be smoother (via the engineering menu typically).

Larry replies: Thanks, Shaun.