Rotoscoping Lightsabers in CinePaint - Version 0.0alpha1
Before we can get started, we need a directory sequence of numbered frames that can be loaded into
the Frame Manager. This tutial will assume that you already have a suitable sequence. Also, I
recomend that you start out in a file format that can handle layers. I personally use
tiff sequences. I have used footage I shot of myself and a wooden stick prop for the lightsaber.
Automatically applying actions to Frames in CinePaint is not currently possible in the current
stable CinePaint release (Version 0.18 as of this writing) and all of your steps will need to be
done manually if you are using a prepackaged version of CinePaint 0.18 or earlier. If you used to
or are willing to compile CinePaint yourself, then some of the burden can be eased. There is a
patch to the CinePaint 0.18 source tree that will allow some layer and filter automations to be
added to the Frame Manager. Hopefully, this will be ready and added into the next CinePaint
release. So if you can not recompile CinePaint yourself, help should be forthcoming.
Load the sequence into the flipbook. If you're lucky you can just load in
the whole thing. For myself, my system and I seem to work best on 10 frames at a time.
In the flipbook dialog select Commands->Layers->New Layer. This will go through each
frame in the flipbook and add a new layer to the top of the layer stack and set it active.
This is the layer onto which we will be rotoscoping our lightsaber.
Now for the time consuming part. Each frame must have the prop lightsaber painted out of it
and replace with our digital version. Using any painting technique you prefer, go through each
frame in the fipbook and paint over the blade prop in white.
Back in the flipbook's dialog. Select Store->Save All to save each frame. Now you can
advance through the rest of your frames repeating steps three to five untill each frame has had
the prop lightsaber rotoscoped out of each frame and replace with a pure white blade.
Now you should have a completely rotoscoped sequence of images. With each image consisting of two
layers. A lower one containing the original frame. And an upper one containing only the white
painted in blade of our new lightsaber.
Now we need to make our rotoscoped images look realistic. For lightsabers, we need to create the
characteristic vibrant colored glow lightsabers are known for. The first step in this process is
to apply a gaussian blur of radius 5.0 to the blade layer. Once you've applied this to the first
frame, you can replay the last filter over the rest of the frames with the menu command
Now we want to make a copy of our blade layer. We can easily accomplish this over all frames with
the menu item Commands->Layers->Copy Layer.
To the new layer we want to again apply a gaussian blur of 5.0, and repeat this accross all frames.
By changing the output levels of different channels on the blade copy, we change the color of the
glow around out lightsabers blade. Right now this is done on a frame by frame basis as the
"gimp-levels" PDB call is not functional.
We should now have three layers. A blured and colored blade layer on top. The white blured blade
in the middle. And the original frame on the bottom. All that is left is for us to composite
the three layers together. This is a simple two step process. On the top layer, the colored and
blured layer, we need to change the blend mode to addition. Commands->Layers->Mode Change
will allow you to quickly change this across each frame.
The final step is to merge all the layers down into a single layer, Commands->Layers->Merge
Visible, and to save the resulting image.