Hello,
I have created a new node (not in svn for now) and I tought that some of you might be interested in it.
Doc is at
http://wiki.blender.org/index.php/User_talk:Xat
and patch is at
https://projects.blender.org/tracker/index.php?func=detail&aid=18012&group_id=9&atid=127
Please do not hesitate to test it and send me your feedback.
xavier
Great, but can you explain the difference between your Keyer Node and a Chroma Key one with Alpha Over ?
Yes I can 
Thechroma key technique is just based on the chroma difference betweem an image and a reference, this permit to isolate any color, mine is just for red green or blue screen. But mine give softer edge and is a much prefered method by many compositor for greenscren or bluescreen.
A chromakey is an historical method form the analogous video world (where signal is YUV) so it is just “a switch” driven by the UV value of the image. Just like a lumakey does with Y channel.
Furthermore, you will need to despill, color correct and composite (with edge blending blur better) this will need a lots of nodes (arround 50) with a lot of redondant/unsused parameters.
My node does all that internally and permit you to choose different method for some operation (no more confusion with mixing the noodles conexions).
If you can put your hands on “Digital compositing for film and video” by Steve Wright, I deeply suggest it to you, it explains all the keying techniques and much more:
Also, if you don’t use my node, you can get better result using the math node (lots of them) then using the chromakey, beleive me chromakey is not the best way to do greenscreen or bluescreen, but it is still a erry usefull technique.
For example in the screenshot image in the doc page, I used a chromakey to get a first matte (which is not really good) then I dilate it and use his invert as a garbage matte.
Hope that help.
xavier
Perhaps it just works better! 
Great, but can you explain the difference between your Keyer Node and a Chroma Key one with Alpha Over ?
I don’t really do this sort of work, but there was a thread here the other day…
apparently there’s lots of shenanigans on things like hair and semi transparent things… they’re easy to “erode” when pullling your key…
usually to fix those things up you need very complicated networks of nodes to process the different colour channels individually and add them together to get a solid matte without degrading the edges horribly
This new node looks very feature rich, very nice indeed… essentially giving you ultimate control with a single node that previously would have taken 20 or more…
Sadly I don’t do blue/greenscreen work, but this makes me want to! (so no tests from me)
thank you very much !
this is a cool development to go along with the video player GE texture
Looks absolutely marvellous! This sort of tool is the kind of thing that will benefit the community immeasurably,
nice one,
Krupa
How do I get this into Blender? And is there anyone that can commit this to svn? I don’t know how to apply patches, but I know how to checkout and scons!! 
Hello,
Thanks for the attention. For now, to test it you have to patch the blender source with my patch before conpiling.
I just saw that you can not folow my first link if you are not registered on projects.blender.org. I will se if I can put the patch on the wiki.
The patch is not in svn as it is waiting to be reviewed by an experimented blender developper. The big amount of parameters and huge UI of the node makes it quite different from the oder nodes, so maybe it will need to be splitted in multiples nodes (or no).
I like to have all in one because for a good composite you almost always have to do all these steps. The big UI was also one of my first preocupation as I want the node to fit well inside blender, but it became dificult to reduce more without taking out some clarity.
Last but not least, the code is bigger then the other nodes (~800 lines) and it seems that I am the only one that have tested it. I managed to obtain great results with all my test, but will it be the case for you?
So maybe it will take some times and polishing but I really hope it can make it to svn before the freeze for 2.5 jump.
xa
Sorry, I forgot to answer the most important!
To apply a patch just do:
patch -p0 < patch.txt
between checkout and scons
Thanks, but , if your patch text file was called something like, ‘keyernode’ I’d write,
patch -p0 < /home/blenderman345/keyernode.txt
right?
Yes,
You must be in the source base directory (just like scons) and if the patch file is int he parent directory:
patch -p0 < …/heyer_patch2.txt
In the sources directory? As in /blenderman345/sources/blender/blendertrunk/blender(sourcesfilelocation)?
I’ll try like that…
yes, exactly.
good luck
I’ve tested the keyer node and works great, but what I thought what was funny is that in the video there’s a greenish bathrobe that was worn and whenever it walked one place it was transparent!
That happen when your matte is not full white in the foreground area, often the easy (but maybe not the best) solution is to lower the “W” value of the scale operation (in the matte pulling parameters).
Hi ! This Node will be a great improvement for compositing with Green/blue screens. I’m sure I will love it. I hope that it will be included in future versions of Blender, because I use Windows, and I have no idea how to get it in Blender. The lines in the post above don’t help me… I assume they are for Linux users ?
usually to fix those things up you need very complicated networks of nodes to process the different colour channels individually and add them together to get a solid matte without degrading the edges horribly
Every solution easier than this is appreciated…
http://upload.wikimedia.org/wikibooks/de/5/5c/Blender3D_com_key_nodesetup_alles.jpg
The whole german wikiarticle about Matte Nodes
http://de.wikibooks.org/wiki/Blender_Dokumentation:_Composite_Nodes_Matte
They are Linux Instructions, I don’t think WinXP has the same filesystem. If this is implemented into SVN, someone will definetaly get a Win build. (Not just Xp, Vista too)
Linux uses a single tree file system, windows is device-oriented.
