[PD] color keying using pd and Gem for OSX

tigital tigital at mac.com
Sun Jun 22 22:03:53 CEST 2003

On Saturday, June 21, 2003, at 08:35  AM, tim cleminson wrote:

> hi,
> 	i am having limited success achieving color keying using 2 stream of 
> video. Have tried using the [pix_alpha] method and can achieve color 
> keying using to picture sources
> or using video as the background and an image as the keyed foreground, 
> but replacing the foreground image with a movie does not work.
> 	tried converting the foreground movie using [pix_rgba] but no use, it 
> just screws up the color. using  [pix_hsv2rgb] results in some sort of 
> keying but not through the pix_alpha method just as a result of 
> shifting the color fields around.
> 	i was wondering if
> 		a) what i am trying to do is just wrong
> 		b) some crucial step is missing
> 		c) GEM implementation on OS X is lacking

hi tim,

...luckily, you just seem to be going about it the wrong way ;-)  There 
are quite a few objects with the latest 0.88cvs version of GEM that do 
this:  pix_composite, pix_chromakey, pix_mix, yuv_luma_key(note to 
self:  needs to be moved to pix_ group), pix_mask, pix_multiply, and 
I'm sure there are others...all of these can mix two inputs together, 
just in different ways...

...don't forget that if you have a rage128 or above, you should 
probably use pix_filmYUV...


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