up for Mac
the weekly newsletter from the producers of Creative Mac. You'll
get news, reviews, features and tutorials, all delivered to your
to see this tutorial on one long page? Click
27 , 2001
How To Make Your Own Adobe Premiere
[Page 2 of 6]
Before we get started
here, you need to know what we're going to be working with. So here's
what we're working with today, along with a little explanation of each
-, /, *): For operations, we simply use +, -, / and * (addition,
subtraction, division and multiplication, respectively). So, 3*3=9.
sliders in Filter Factory are referred to as controls, abbreviated
"ctl," followed by a number representing the particular
slider. They are numbered 0 through 7, rather than 1 though
8. Ignore the "Map" labels. They don't mean anything
for this tutorial.
- Sliders (ctl(0)
though ctl(7)): To specify which slider you want to have control
over a particular aspect of your equation, signify the control as ctl(0)
through ctl(7). That's eight controls, numbered 0 though 7. So, if ctl(0)
is set to 3 and ctl(1) is set to 3, then ctl(0)*ctl(1)=9.
- Pixel Coordinates
(x, y, X, Y): We're also going to be using x, y, X and Y. These
represent horizontal and vertical pixel coordinates. Lowercase x and
y represent the current position of each individual pixel. Uppercase
X and Y represent the edges of the image. So, if you want to move all
of the pixels in your red channel, for example, you could write "x-3,y-3"
in the R field. This will shift your red channel down and over by three
pixels. Or you could write "x-ctl(0),y-ctl(1)," which would
shift your red channel down and over a number of pixels equal to the
current value determined by the position of the first and second sliders.
- Function (src):
Now, we also have to use a couple of functions. Literally just a couple
in the beginning. The first one is src. This src function is just used
to tell Filter Factory where it's supposed to pull its pixel information
from, namely your image. So, instead of simply writing "x-ctl(0),y-ctl(1),"
you write "src(x-ctl(0),y-ctl(1)). It's basically just a formality,
but you have to do it to get this to work properly. One other thing
you have to do is to specify a channel in your src expression. This
is simply a matter of placing a number 0 though 3 at the end of the
expression so that it looks like "src(x-ctl(0),y-ctl(1),1)."
- Function (rnd):
Finally, for this tutorial, we will introduce the random function. This
is a great one for generating noise effects. Basically, all you have
to do is write something like rnd(1,30) to generate a random number
between 1 and 30. Of course, you can use controls instead of absolute
numbers. In other words, something like src(x-rnd(ctl(0),ctl(1)),y-rnd(ctl(2),ctl(3)),1),
which will offset your pixels by a random number between the values
set by your sliders. Quite handy for bringing in gradual noise.
So these are all the
things you have to know to get started. So let's get started.
Example 1: hue
Just to start off, so you can see that this thing actually works, go into
the Filter Factory in Premiere and set the R, G and B text fields to ctl(0),
ctl(1) and ctl(2), respectively. Then play around with the first three
sliders. Notice something? You're just getting solid colors. But when
you move the sliders back and forth, the color changes depending upon
the value for each channel.
Neat, but useless.
So let's add in some practicality. This time we're going to try a hue
shift. All we have to do for this is is take the default value of each
cannel and add or subtract some slider values. So the red channel, for
example, will read "r+(ctl(0)-ctl(1))."
TO PAGE [ 1, 2, 3,
a message in the Creative Mac World
Wide User Group.