The LumaKey node has changed in CVS to the Channel Key node, but now I can’t work out how to get the same results with the Channel Key node as I did with the LumaKey node. There are now four options for which colourspace to operate in: RGB, HSV, YUV and YCC. The only one where I seem to get fairly decent results is using the saturation option for HSV, but it still isn’t as good as say the results got with the LumaKey node as in the example on the wiki: here
Oops, I think you found a bug! Looks like I have the alpha channel being generated the opposite of what it should be. I’ll see about getting it fixed pronto for you.
Ok, I’ve looked it through and have a solution. What you are seeing is technically correct, but is backwards from what the luma key produced. This is because the luma keyer was specific to luminance and took into account that you wanted to keep the higher luminance value, but the new channel keyer assumes that you want to mask the highest channel (works well for green/blue screens).
That being said, to get the same results all you need to do is add an RGB curves node to the matte image that you are producing and make the line run from the top left to the bottom right (essentially inverting the image).
Sorry about the confusion and I’ll look at other alternatives (ie. reintroducing the luma key node). I hope this helps.
cheers,bob