Joe Maller: FXScript Reference: Building Joe's Motion BlurHow I used FXScript to build my Motion Blur filter for Final Cut Pro.
Joe's Motion Blur is a replacement for the Wind Blur filter included with Final Cut Pro. This directional filter sacrifices speed for quality, but ends up with a much more aesthetically pleasing effect than the built-in filter produced.
Unfotunately, FXScript's built in
Not much to it
There is almost nothing to this filter. Initially there are a few lines to declare variables and set up
The last option in the motionBlur() function sets the number of intermediate steps. This was the major stumbling block of Wind Blur. The smoothest possible blur would have the number of steps equal to the distance, one step for every pixel. However, in most cases there is no perceptable difference between a step for every pixel of distance or every 3-4 pixels of distance.
The trick was not to set an arbitrary amount, but to set an amount dependent on the distance specified. BlurQuality is a slider between 1 and 10. This value is translated to match whatever distance is set with the following line:
The reason to divide by 20 instead of 10 is because of how
Now all that's left to do is the actual blur. The distance is measured in x and y coordinates, using Sin and Cos to translate the angle. (Using Sin and Cos for angle translation is covered with Building Joe's Gradients.) The following needs to appear on the same line in the actual source code:
As you can see, there's not much too it. The filter finishes with my standard compositing controls, mixing
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