This is my final post in the HDR series. I’ve already discussed the basics of HDR photography and how I batch the HDR images. This post is about finishing the process by eliminating flicker from your video.
What causes flicker?
Flicker occurs when each frame of a video has a different overall brightness. When I began making time lapse videos, I often encountered some degree of flicker. It was usually caused by forgetting to set the exposure manually, but it can also result from too small of an aperature or even an inconsistant camera. Most of the time, I discarded the final footage.
In HDR photography, three to five images of different exposures are merged into one image. Even though I use the same program with the same settings to process every image, there’s often enough difference in brightness between images to cause some flicker. This difference becomes much more noticeable when the exposures are farther apart and when the HDR is strenghtened in processing, as shown in the above example.
I’ve talked before about the free video software VirtualDub. One of the advantages to this software is that there are plenty of free filters available online. I use the MSU Deflicker Filter in almost all of my HDR videos.
To install the filter, visit their site and find the download link toward the bottom of the page. There’s an interesting overview of video flicker, a tutorial on using the filter, and links to some of their other free filters, so you might want to take a minute to read the whole page.
After you’ve downloaded the filter, unzip it and move the .vdf file to VirtualDub’s plugin folder. On PCs, this folder is usually located here: C:\Program Files\VirtualDub\plugins
Choose the default settings if it’s your first time using this program, select your usual compression settings, and open the video file that has flicker. Select File>Save as AVI… and choose a name and location. Your video should now be flicker free. If the filter causes any problems such as the video being too dark or if it doesn’t remove enough flicker, go back and adjust the filter settings until you’re happy.
If you make any HDR videos using this method, please post a link in the comments. Good luck!