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Posted by PTravel on 10/09/06 20:27
"Rayne" <mineapollo@gmail.com> wrote in message
news:1160399746.466405.211350@b28g2000cwb.googlegroups.com...
> Hi guys, ive been struggling trying to understand something here. Has
> anyone seen (hard to describe) adverts and title sequences made using
> stills. Pics of people or things that have been cutout and rotated
> about the z-axis? Channel 4 used to make a whole lot of these adverts
> at one point using this kind of technique...im trying to work out how
> to do that kind of thing, either to use after effects or Motion to
> create movement using stills. Help? I know its a bit tough to
> describe..ill try and find an example and post back..
>
I think I know what you mean.
The first step is to separate the subject from the background. This is done
using a still image editor, like Photoshop. Start with two copies of the
original still. On one, use "magic lasso," "background remover" or some
similar tool to isolate the primary subject. Save the still in some format
that preserves the alpha channel.
On the other copy, use the "Healing brush" or "clone tool" to extrapolate
the missing background that was behind the primary subject.
Import both stills into a video editor or effects program that can work with
alpha channel and allows superimposition. Place the still with the primary
subject over the still with the extrapolated background.
Using movement tools, setup a slow zoom or pan on the still with the
background. Do the same thing with the primary subject still, but increase
the speed and "distance" moved (this is an old animation technique
originated when cartoons were drawn on cels -- there's a name for it, but I
can't recall at the moment).
The resulting video makes the scene appear as if it was three dimensional,
with the primary subject positioned in front of the background.
Because the "hole" left in the background still when the primary subject is
removed must be filled in, there is no way to create the entire effect in a
video editor or effects program (at least none that I'm aware of). Also, if
you don't have anything that works with alpha channel, you might consider
positioning the primary subject on a green or white background and using
chroma- or luminance-keying in the video editor, respectively.
>
> M
>
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