Alpha channel support

[mrtenda]

Hi, does LivePortrait support source images with an alpha channel?

Support for transparency in source images would allow a lot of very interesting use cases, so I think this would be a valuable feature. It would allow for the separate modification of face expressions independent of the background while doing video production/compositing work.

Unfortunately, it seems like LivePortrait does not currently support transparency, as when I tried to use the image below with ComfyUI, the alpha channel is ignored.