emission on transparent background?

[Dingbat]

how would i go about getting the red emission on it's own transparent layer?

[bepeg4d]

Hi,
if caused by Post Effect, please have a look at here:
viewtopic.php?f=9&t=78227&p=403544&hili ... ha#p403544

ciao,
Beppe

[Dingbat]

thanks but it's not an effect

the red light comes from an emitter behind the panel (it's a tv panel with perimeter strip light) and is illuminating the wall behind

i'd like the wall to be invisible and the red light visible on a transparent background

[elsksa]

Have you explored render layers, AOVs, etc?

[Dingbat]

i have tried and the closest i got was emission on a black background but AFAIK there's no way to composite that on a white background?

[elsksa]

The black background is likely "emptiness" in the absence of encoded "alpha" transparency data. Technically, it should be possible, how (to do it in comp) is a question for an experienced compositor.