How to Make a Temporal Median Filter in Shake

(“Bravia” commercial clip Copyright SONY.)

Temporal Median Filters work like magic for removing small unwanted objects from video . . . like hairs and dust. I’ve often wished I had a Temporal Median Filter to remove unwanted noise from my videos. I always figured that Shake was flexible enough to do the job with just the available nodes, but I couldn’t figure out how to do the job until recently. I’ve made a macro out of my work which you can download here. Technical details follow.

I tried and failed with the LayerX node because it can’t do pixel-wise comparisons, and the TimeX node can only work with one FileIn node. But the ColorX node can do the job . . . if you can feed it the right information. Here’s what you do:

1) Create 3 FileIn nodes all with the same video source.
2) Edit the Timing>Timeshift parameters of one FileIn node -1, and another to 1.
3) Reorder the three video sources so that each only has the red channel. For video source 2, the red channel is reordered to the green channel, and for source 3, the red channel is reorder to the blue channel.
4) Combine all three video streams with a couple of IAdd nodes.
5) Add a ColorX node with this formula in the Red channel:
r+g+b-Max3(r,g,b)-Min3(r,g,b)

Red Temporal Median Filtering Shake Node Tree

6) Repeat steps 3-5 for the green and blue channels.
7) Layer all the data together with some reorder and add nodes.

Complete Temporal Median Filtering Shake Node Tree

And if you don’t care to do all that, here’s a picture of the simple tree you’ll need to make after using my macro:

Temporal Median Filter Shake Node Tree

You can download the complete MedianTime macro here: MedianTime Filter at Creative Crash

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