We’re releasing a simple tool today to help you reduce noise in ’09. We develop many 3D filtering tools at AT, but this one is a good candidate for release because it’s useful for video compositing.
MedianInTime performs a median filter over time for each pixel. The median filter kernel can be selected from sizes 3,5,7 or 9 (indicating the total number of frames in the sort). The tool calculates the median based either on the luminance or the RGB channels separately. This operation will generally reduce noise, but is also great for removing things that appear for just one or two frames such as rain drops, film artifacts, and subliminal advertising.
I rendered two examples to demonstrate the technique. The first video shows how objects moving quickly in relation to other content can be removed with the median filter. In this example the stars moving in this time lapse footage are removed (as well as the odd shooting star).
The second video is a vintage cartoon with prominent film artifacts. These are efficiently removed with a 1x1x5 filter, although at the cost of slight ghosting for some of the faster moving scenes.