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 Tutorial - Fixing Back Lighted Videos in Premiere Pro

Problems arise when you shoot video with a bright light in the background, which is often called a backlight. When in automatic exposure mode, the camcorder assumes that the bright light is too bright, and darkens the entire video to compensate. When your subject is in the foreground, this often results in your subject being too dark, as shown in the first figure, which, as with all images in this tutorial, you can click to see in a larger picture.

Now the best way to deal with backlighting is to avoid it, which you can do by repositioning the light, repositioning the camera or by using a backlight adjustment on your camcorder. Sometimes in the jumble of a shoot, you forget to do any of these, and often an overly bright LCD screen on your camcorder hides the fact that you may have a problem. 

After you've captured the video, if you apply a standard brightness and contrast filter, you'll adjust the values over the entire image when the desired effect is to brighten only the darker regions. Fortunately, Premiere Pro (and Elements for that matter) has a filter called Shadow/Highlight (in the Adjust group) that does just that. Overall, it's pretty simple to use, but their are some caveats.

First, even on a dual 3.6 GHz Xeon Dell Precision workstation 670, experimenting with the filter was very slow with my 45 minute project. So isolate a short segment on the timeline and experiment with that before starting to work on the entire project.

Second, though the filter has an automatic mode, you may have to tinker to achieve the optimal (or even an acceptable result). For example, when I went 100% automatic over the duration of my video, the filter boosted light too strongly on some lighter regions of the clip, producing a noisy effect very similar to what you see when you boost gain too much on your camcorder.

Note that this noise wasn't clearly evident until I played a test DVD on my television set. The noise wasn't terribly apparent on my computer monitor, or even an NTSC monitor connected to my editing station. So if you use this filter, I recommend producing several short files using different settings, burning them to a DVD and watching them on your big screen TV before making your final selection.

How much you tinker with the settings is up to you. You can go completely custom with about 8 different parameters to adjust, but you'd have to manually compensate for small changes in lighting throughout the original clip, which I calculated would take roughly forever on my project. I went fully automatic, but adjusted the Blend with Original control to changing light conditions. This control determines how closely the adjusted video tracks the values of the original video. With a setting of 0, the filtered clip is used with no blending, at 50 the ratio was 50/50 and at 100 the original clip is used with no blending.

When lighting was reasonable in my source video (and backlighting not terrible), I went with a value of 25-30. When backlighting was at its worst, I went with around 10. This produced the image shown on the left. If you compare it to the top image, you'll note that the background light is almost exactly the same, but the foreground image has been brightened considerably, which is just the effect that I wanted.

Many other editors have filters that can help alleviate backlighting - for a survey of consumer tools, see http://www.doceo.com/con_editors/corrective.htm.

For the record, rendering the video took about 80 minutes on said Dell Precision workstation, and I had to do it three or four times to get it right. Be sure to factor long rendering times into your time budget and delivery schedule.