QUOTE(detbear @ Mar 8 2012, 05:14 AM)
ACTUALLY.....you can overlay a jpeg shadow using Multiply mode in PS or AE but I agree that it isn't ideal.. I wish that at some point an easier method of separating shadows in rendering could be done. It would require a layered render option that would give several files for each frame.
AS I mentioned before, the EXR output does this currently, but it isn't a straight forward process either.
This option is available from v16 on without EXR.
You just have to set your format to TGA. After that, set "LightBuffers" to on and any additional buffer you want to and there will appear two new options called "Save Buffers" and "Save Lightbuffers" which should be set to "on".
When you render now, A:M will save these buffers out as seperate files with a name like "xyz_ShadowBuffer", etc.
You need to use Multipass to get these buffers out.
In v17 there is a bug in this... I dont know if it has been around for longer so. I will create a bug report on it.