Paint and Cloning

Paint and Cloning

Paint is generally a last resort when roto is impractical, and
for a simple reason: Paint work is typically painstaking and
more likely to show fl aws than approaches involving masks.
Of course, there are exceptions. The ability to track clone
brushes offers a huge advantage over masks, which are not
so easy to track, and painting in the alpha channel is akin
to masking with paint.
For effects work, paint controls in After Effects have at least
a couple of predominant uses:
. Clean up an alpha channel mask by painting directly to
it in black and white
. Clone Stamp to overwrite part of the frame with alternate
source
Once you fully understand the strengths and limitations of
paint, you can come up with your own uses.

Paint Fundamentals

Two panels, Paint and Brush Tips, are essential to the three
brush-based tools in the Tools palette: Brush , Clone
Stamp , or Eraser . These can be revealed by choosing
the Paint Workspace.
The After Effects paint functionality is patterned after
Photoshop, but with a couple of fundamental differences.
After Effects offers fewer customizable options for its
brushes (you can’t, for example, design your own brush
tips). More signifi cantly, Photoshop’s brushes are raster
based, while After Effects brushes are vector based, allowing
them to be edited and animated at any stage.
Suppose that you have an alpha channel in need of a
touch-up; for example, the matte shown in Figure 7.15 is a
diffi cult key without matte cleanup due to tracking markers
and shadows. With the Brush tool active, go to the Paint
palette and set Channels to Alpha (this palette remembers
the last mode you used); the foreground and background
color swatches in the palette become grayscale, and you
can make them black and white by clicking the tiny blackover-
white squares just below the swatches.


To see what you are painting, switch the view to the Alpha
Channel (Alt+4/Option+4); switch back to RGB to check
the fi nal result.
When using the paint tools
. Brush-based tools operate only in the Layer panel.
. Brushes include a Mode setting (analogous to Transfer
Modes).
. With a tablet, you can use the Brush Dynamics settings
at the bottom of the Brush Tips palette to set how the
pressure, angle, and stylus wheel of your pen affect
strokes.
. The Duration setting and the frame where you begin
painting are crucial.
. Preset brushes and numerical settings for properties
such as diameter and hardness (aka feather) live in the
Brush Tips panel.
Much more fun and interactive than the Brush Tips panel
are the following shortcuts. With the Brush tool active in
the Layer viewer


. Hold Ctrl/Cmd and drag to scale the brush.
. Add the Shift key to adjust in larger increments, and
Alt/Option for fi ne adjustments.
. With the mouse button still held, release Ctrl/Cmd to
scale hardness (an inner circle appears representing
the inside of the threshold.
. Alt/Option-click to use the eyedropper (with brushes)
or clone source (with the clone brush).




By default, the Duration setting in the Paint menu is set
to Constant, which means that any paint stroke you create
on this frame continues to the end of the layer. For cleaning
up an alpha channel, this is typically not a desirable
setting because you’re presumably painting stray holes in
your matte here and there, on single (or just a few) frames.
The Single Frame setting confi nes your stroke to just the
current frame on which you’re painting, and the Custom
setting allows you to enter the number of frames that the
stroke will persist.
The other option, Write On, records your stroke in real
time, re-creating the motion (including timing) when you

replay the layer; this stylized option can be useful for such
motion graphics tricks as handwritten script.
The Brush Tips panel menu includes various display
options and customizable features: You can add, rename,
or delete brushes, as well. You can also name a brush
by double-clicking it. Brush names do not appear in the
default thumbnail view except via tooltips when you move
your cursor above each brush.
For an alpha channel, you will typically work in Single
Frame mode (under Duration in the Paint panel), looking
only at the alpha channel (Alt+4/Option+4) and progressing
frame by frame through the shot (pressing Page Down).
After working for a little while, your Timeline may contain
dozens of strokes, each with numerous properties of its
own. New strokes are added to the top of the stack and are
given numerically ordered names; to select one to edit or
delete, you may more easily fi nd it using the Selection tool
(V) to directly select it in a viewer panel.