Remove black from RGB channels on render

Another “old PI” question. When rendering in the old pIllusion render there was an option under Alpha Channel to “remove Black from RGB channels”. Is that option still included anywhere? Has it been renamed? All info appreciated!

That option does not exist anymore, but with the flexibility of the new compositing methods, it’s probably not needed.

If back in the host you select “Classic” under the compositing section, PI will render directly on the background image as pI3 did – you shouldn’t see any black fringing using this method. If you select “Alpha + Apply Modes” instead and select a compositing mode, you may see some fringing depending on the transfer mode selected.


Thanks, Alan! What I am trying to do is isolate an effect on some footage without the background. I’ve tried doing it on a green background and keying the background out but I do get the black fringing. Maybe I’m trying to do something the hard way that can be done an easier way? What I am shooting for is footage that has a transparent background but the emitter is intact. I hope that makes some sort of sense.

Just apply PI to the footage layer. If that won’t work for you, a screengrab might help me understand better.

Hi Alan. I knew I didn’t explain it very well. Let’s say I have a picture of a valley and I want to show a distant campfire. I overlay the campfire emitter onto the valley footage and try to resize it in the emitter parameters but it doesn’t look right. If I could render the campfire, full size, alone on a transparent background then I could place the fire in the valley and manipulate the campfire size with pan/crop or track motion. I have a screengrab and will try to upload it.

I may have figured out what to do. I was trying to resize the emitter solely with the “size” parameter(s) and was not using the “zoom” parameter - which (I think) will achieve the effect I want. I still need to squeeze down the emitter’s box but that’s easy to do. I am still open to any input you’ve got though! Thanks.

Back in the native plugin UI you can change the Composite Style menu to “Alpha + Apply Mode” and it will generate just the particles over transparency which you can then manipulate/resize as desired before doing the final composite - perhaps with a Screen or Add mode. Note that if you change the native Transforms menu to World you then get some basic scale and offset controls you can use to fine tune the placement back in the native UI if that’s easier - as well as the native Particle Properties controls for Zoom/Scale/etc.

Thanks jclement! That is it. In addition to setting it to "Alpha + Apply ", transforms to “World” , and Apply Mode to “Normal”, I then used “Master Scale” under “World Transform” to accomplish the sizing task in a way that works for me. THANK YOU!