In this how-to I will replace my shadow with another one by applying a mask on the first one. Masking permit you to isolate a specific region of a picture for special treatment.
While I’m smoking my shadow is drinking water because it is dehydrated.
This little video was inspired to me by a photo from Clarisse a nice girl of the Netlog social network:
“You should not give too much freedom to your shadow” Clarisse.
To make this effect I had to do all the sequences in only one take.
Why? Because the use of mask for these sort of videos needs same weather, same light, same background, same camera position (or same move) etc …
You already know: Open Cinelerra, prepare your project (size, framerate, color model etc) in Settings -> Format according to the media you will use or the destination of your final work.
When done, load the video you want to modify on the first track of the timeline.
The video I want to modify: my shadow is smoking just like me.
If you apply a mask right now on your video it will appear like a black hole drawn on the picture.
How to draw a mask:
- In the compositor window click on the Edit mask tool
. The mouse pointer change for a cross pointer that indicate you can draw right on the picture. - Use the splines to make a shape that surround the subject(s) you want to eliminate. There you guess that’s where this technique can become arduous: if the subject is moving you will have to follow his movement by modifying the mask shape or moving it (with Ctrl Alt Click).
- The Show tool info button (question mark
button) open a dialogue box and give you more options to change the mask: mode, opacity, smoothness of the edges… I let you discover them.
The mask appear like a black hole in the picture. Substract alpha mode eliminate the subject, multiply alpha mode isolate the background of the subject.
Now you can load the video containing the new subject in a track below your first track. That’s all!
In fact steps 3 and 4 can be inverted but well it’s an how-to.
Last word: Masks are keyframable; that means you can change their attributes along the time using keyframes (which are viewable with View -> Mask).
There are different methods to isolate a specific region of a picture. It is possible for example to select an object by it’s color. Drawing a mask with splines is just one of them.
Masking is also used to blur someone’s face for example, to emphasis a character by bluring his surroundings, to make clones, or other artistic effects.
Another use of masking with Cinelerra.
What about a contest to imitate this sequence of Lucky luck cartoon?:
What about a contest?
Other videos made with Cinelerra playing with masks:
– Being by myself from devapea
– Cinelerra masking from Tatucik
– Mi clon y yo from pedroIramon
– Core 2 duo from zoelans
– Clones from strongpiggie
– Cinelerra Magic from Kris Czerniawski
– Intro Guerrilla y nuevos movimientos sociales from Victor Zamora
