NTP3: RGBA Channels and Premultiplication for VFX Compositing

[@streamsandgalaxies]

Hello once again!... it looks like I can't post external links. My parametric mask layers were unfortunately saved as RGB even though I saved the whole Tiff image with alpha so when I try to shuffle and merge with my original image, the subject (A) is slightly transparent and the background (wether B pipe or mask) not fully transparent when I try to use my image sequences in my video editor (the desired background is actually video thus easier to composite furthur in the video editor). I wonder if there is a roto tool in Natron that could 'read' my mask layer automatically...

[@HarryChrisp]

Use the shuffle node to send the red channel to the alpha channel

[@bharatthakur9588]

Hey brother, can you provide tutorial on how to make twixtors or super smooth slow mo clips in natron? Thank you!

[@HarryChrisp]

Looks pretty cool, I’ll definitely check it out and if I can get it working well yea I’ll make a tutorial on it!

[@streamsandgalaxies]

Hello! I have multiple images (sequenced) with layers saved in Tiff (with alpha) but my layers were composed of parametric masks based on luminosity thus I have a layer where visually the subject is white while the background is black (and even for some sequences, a layer that is the opposite), but I didn't know how to convert the parametric masks to an matte or alpha layer in the photo software. How do I convert the layer to an alpha layer (even if they are not perfectly black and white)? I keep using the temp shuffle (community plugin) for layers or the shuffle node but when I try to re-merge with my subject, I can't get the background out. Can it be done in either Natron or Nuke? Otherwise I am stuck going back over a thousand images and attempting to convert to alpha in photoshop...

[@HarryChrisp]

Hi, yes that definitely sounds possible to do over a sequence in Natron. The Alpha doesn’t have to completely black or white; it works on a floating point between 0-1. I’m struggling to follow the specifics of what you’re describing without seeing the images but from what I gather you should be able to accomplish your goals by shuffling out the colour layer you want then the matte layer and finally copying the matte layer into the alpha channel of the colour layer. That will give you a four channel (RGBA) image

[@streamsandgalaxies]

@@HarryChrisp Hello again, thnks for quick reply! I can't get to my project at the moment but I know there was a peculiarity in the channel components of the parametric layers which I don't quite understand how to handle. I can repost with the specifics within the next 24hrs... would greatly appreciate!!