Perfect Alpha?
polycounter lvl 14
Hi I have been cutting a lot of the stuff out for getting a perfect alpha on this image , but then when I try to transform this into an alpha channel it gets reallybad with lots of white halo etc , how can I do to use the actual cutted out part to form a decent alpha?
Replies
Adjust curves or levels til all your stuff is black against white
Ctrl-A Ctrl-C
Paste in your alpha channel
Photoshop has a bunch of other methods too, like Select > Color Range, etc.
As mentioned, CTRL-clicking this layer will make a new selection based on the existing transparency, you can then fill this selection in as white on a black background.
However, you will then need to make sure your diffuse has some padding. I suspect the white pixel "bleeding" you're talking about is due to not padding the diffuse out at all, so the transparent background is showing through when you apply the alpha channel in your 3D app.
if your lucky enough to have your subject against a primary colour you can use the channel mixer to create a alpha.
Put in in monochrome mode. put the background colour to as low as it will go and then ramp up the constant slider.
then use the result as a layer mask.
This one was quick, you can get more subtle with it
If your feeling fruity you could also try After effects or Shake and pull a key with keylight. hell Max and maya come with a compositor now. they should have good keying features.