I was wondering whether it is possible convert a specific color, like
green-screen chroma key, to alpha information using Gem. They idea is
to overlap many green-screen videos. I can see the pieces, but I
can't see the whole.
.hc
Man has survived hitherto because he was too ignorant to know how to
realize his wishes. Now that he can realize them, he must either
change them, or perish. -William Carlos Williams
Hans-Christoph Steiner wrote:
I was wondering whether it is possible convert a specific color, like green-screen chroma key, to alpha information using Gem. They idea is to overlap many green-screen videos. I can see the pieces, but I can't see the whole.
Maybe use a GLSL fragment shader to do the colour to alpha mangling? Should be superfast on a recent GPU with supporting drivers...
I have done a lot of this type of processing with a shader. Just pick the color in the desired range and set the alpha of a pixel in that range to 0. After that just lay the video on top of each other.
On Mon, Apr 20, 2009 at 3:34 PM, Hans-Christoph Steiner hans@at.or.atwrote:
I was wondering whether it is possible convert a specific color, like green-screen chroma key, to alpha information using Gem. They idea is to overlap many green-screen videos. I can see the pieces, but I can't see the whole.
.hc
Man has survived hitherto because he was too ignorant to know how to realize his wishes. Now that he can realize them, he must either change them, or perish. -William Carlos Williams
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I haven't written a shader before, anyone have one they could share?
Or is this possible without shaders, i.e. just Gem objects?
.hc
On Apr 20, 2009, at 3:55 PM, chris clepper wrote:
I have done a lot of this type of processing with a shader. Just
pick the color in the desired range and set the alpha of a pixel in
that range to 0. After that just lay the video on top of each other.On Mon, Apr 20, 2009 at 3:34 PM, Hans-Christoph Steiner
hans@at.or.at wrote:I was wondering whether it is possible convert a specific color,
like green-screen chroma key, to alpha information using Gem. They
idea is to overlap many green-screen videos. I can see the pieces,
but I can't see the whole..hc
Man has survived hitherto because he was too ignorant to know how to
realize his wishes. Now that he can realize them, he must either
change them, or perish. -William Carlos Williams
Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
"[T]he greatest purveyor of violence in the world today [is] my own
government." - Martin Luther King, Jr.
Hans-Christoph Steiner a écrit :
I haven't written a shader before, anyone have one they could share?
yes, there are some in the Gem examples. example/10.glsl directory
Or is this possible without shaders, i.e. just Gem objects?
pix_alpha does it, but it's very basic.
pix_coloralpha can do it with other pix_objects.
Cyrille
.hc
On Apr 20, 2009, at 3:55 PM, chris clepper wrote:
I have done a lot of this type of processing with a shader. Just pick the color in the desired range and set the alpha of a pixel in that range to 0. After that just lay the video on top of each other.
On Mon, Apr 20, 2009 at 3:34 PM, Hans-Christoph Steiner <hans@at.or.at mailto:hans@at.or.at> wrote:
I was wondering whether it is possible convert a specific color, like green-screen chroma key, to alpha information using Gem. They idea is to overlap many green-screen videos. I can see the pieces, but I can't see the whole. .hc ---------------------------------------------------------------------------- Man has survived hitherto because he was too ignorant to know how to realize his wishes. Now that he can realize them, he must either change them, or perish. -William Carlos Williams _______________________________________________ Pd-list@iem.at <mailto:Pd-list@iem.at> mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
"[T]he greatest purveyor of violence in the world today [is] my own government." - Martin Luther King, Jr.
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