-
keying out black background on generated vid clips?
Ello all,
Im sure this is probably a reposted question but I dont know what to look under.
Ok so, my question is: how do I key out a solid black background with a generated clip? I have made an explosion/fireball sort of effect that, once it is rendered in a seperate program it has a black background. If I try the mode transfer options in AE, such as lighten or screen, it eliminates too much of the effect, washing it out once it is placed above the main video clip. Is there a better way to do this?
-
7 Replies
-
You should check to see if your program can output with an alpha channel. If it can, re-render, preferably as Straight, not premultiplied.
Look here for more info:
Alpha Channels:
https://cowcast.creativecow.net/multimedia_101/episodes/CC_101_AlphaiPod_Lo.mp4
Straight Vs. Premultiplied:
https://cowcast.creativecow.net/multimedia_101/episodes/CC_101_StraightiPod_Lo.mp4
If that’s not an option, perhaps try rendering over a blue or green BG and then using Keylight to remove the BG. I’ve done it that way with smoke. Not because I had to, but because I wanted to see how good keylight really was.
—————————————-
Aharon Rabinowitz
arabinowitz(AT)yahoo(DOT)com
http://www.allbetsareoff.com—————————————-
Click the link below to subscribe to the Creative Cow After Effects Podcast, and get free AE video tutorials:https://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=111087911
-
-
Thank you for the tip. I duplicated my explosion clip twice and the clarity came through great! Seemed like the easiest method and it worked like a charm. Thank you for all the tips!
-
As you now know, you can get some pretty decent results from using different blending modes at different opacities. I usually like to use Screen, Add and Soft Light (in that order). Screen generally looks a little muted, which is where Add and Soft Light come in. Add is a little blown out so I usually lower the opacity some, but it gives a nice glowy feeling to the explosion. Soft Light adds some contrast to the underlying layers.
However, the ‘proper’ way to do this is to linearize the working space and work in at least 16bpc. In AE7 you can do this in the project settings, there’s a checkbox under the color profile selection for Linear Blending. Then just use the Add blend mode.
-
Darby – just wanted to say – I’ve noticed you posting a LOT lately. Your advice is great, and your sharing your knowledge is greatly appreciated.
Aharon
—————————————-
Aharon Rabinowitz
arabinowitz(AT)yahoo(DOT)com
http://www.allbetsareoff.com—————————————-
Click the link below to subscribe to the Creative Cow After Effects Podcast, and get free AE video tutorials:https://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=111087911
-
Yes indeed, thank you for the great tips! I tried a couple of the methods and they both worked well. One step further!
-
Thanks Aharon, I’ve actually learned a great deal as well. This forum is one of the most valuable sources I’ve found for real world creative and technical advice from AE pros. I just like to try to give back when I can =)
Darby Edelen
DVD Menu Artist
Left Coast Digital
Aptos, CA
Reply to this Discussion! Login or Sign Up