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TUTORIAL FEBRUARY 27 , 2001
How To Make Your Own Adobe Premiere Filters

[Page 5 of 6]

Example 3: bring in the noise
In our final beginning example, we'll introduce the concept of random pixel offsets. Using the random, or "rnd," function, we can tell Filter Factory to shift individual pixels in our video by a random amount in between two numbers we give it. These two numbers can be either static or dynamic (based on slider values), depending on how much control you want.


Our video with simple noise applied.

The advantage of random values is that it creates noise in the channels that can have some pretty slick results when combined with standard channel shifting, which we learned in the previous example. To generate a random value, instead of using, for example, x-ctl(0), you would use x-rnd(1,30) to generate x minus a random number between 1 and 30. Or you can generate a random number between two controls, such as x-rnd(ctl(0),ctl(1)), which generates x minus a random number between the values of ctl(0) and ctl(1).

Let's try it out. We're just going to modify the formula above thusly:

Now rather than watching our channels shift, we're watching them shift as they break into particle-like noise.

Now try mixing up all of the examples we've put together. Use a hue shift formula in the R field, a channel shift in the G field and a noise formula in the B field. Or use a channel shift in an x coordinate and a noise generator in the y coordinate, such as R: "src(x-ctl(0), y-rnd(ctl(1),ctl(2)),1)." Or some such. Try different operators as well. Try multiplying and dividing, for example.

Of course, this isn't all the Filter Factory can do, but it will give you a start in terms of figuring out how to make things happen. In another tutorial, we'll look at more complex functions, as well as methods of passing and returning data.

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