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Creating a Lens Flare with alpha ON TOP of another image -> Premiere

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Jennifer Jones
Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 18, 2013 at 10:05:44 pm

Hi -

I know this question has been posted in various forms, but none with this combo - Basically, I'm trying to create a lens flare on top of an image, rendering the whole thing from AFX with an alpha channel, and plopping it on a sequence in Premiere (without changing the layer mode to screen in Premiere - which, I don't think you can do in Premiere??)

In any case, I'm trying to make it "dummy proof" for the editor, so they can just import the QT into premiere, and voila! there's a lens flare over the image, and an alpha channel already there.

So far, in After Effects, I've pre-comped the lens flare with a black solid, and changed the solid's mode to screen, but when I render this with an alpha, I still get the black BG when I bring it in Premiere.

Any help would be greatly appreciated! (AND, a step-by-step would be TOTALLY appreciated!)

Thank you in advance,
Jennifer


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Dave LaRonde
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 18, 2013 at 11:01:01 pm

It's kind of tough to dummy-proof a lens flare for an editor. The reason: they look best when use a blend mode on them, like Add or Screen. If the NLE in question can do it, that's great. Not all can.

But you CAN take the flare -- in a precomp if made in AE -- and do the following:
  • Add the layer to a comp & duplicate it.
  • Add the Set Channels Effect to the top layer. Set the Alpha to luminance, and turn everything else off.
  • Use this layer as an Alpha Matte for the layer below it.
  • Render as an alpha-cannel movie.


Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Greg Leslie
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 20, 2013 at 3:45:56 am

Wouldn't it be best to also render the movie as "straight-unmatted" to get rid of dark halos on transparent areas? I usually do that when I output a ProRes 4444 that I'm going to key elsewhere...

Greg Leslie
Broken Arrow, OK


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Walter Soyka
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 20, 2013 at 3:58:08 am

[Jennifer Jones] "Basically, I'm trying to create a lens flare on top of an image, rendering the whole thing from AFX with an alpha channel, and plopping it on a sequence in Premiere (without changing the layer mode to screen in Premiere - which, I don't think you can do in Premiere??) "

Premiere has blend modes. They're located in the Opacity twirl-down of the Effects Control panel [image]:



It just takes a couple clicks to set it, and you'll get a much nicer composite.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Darby Edelen
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 20, 2013 at 4:26:07 am

With the lens flare on a black solid apply the channel>shift channels effect and set the alpha to luminance. Then apply the channel > remove color matting effect. That should do it.

Correct interpretation of the alpha in your NLE will be important.

Also: premiere does have blend modes.

Darby Edelen


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Jennifer Jones
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 21, 2013 at 12:18:05 am

Ah thank you all! Sounds like it's best to use the (newly discovered)
Premiere screen mode.. will give it a shot tomorrow. Thanks again!


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Kevin Camp
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 21, 2013 at 6:46:35 pm

if you wanted to key it, i'd modify darby's recipe slightly and use the channel combiner effect, setting 'from' to max rgb and 'to' to alpha, then add the remove color matting effect.

this will keep all the color saturation (using shift channels will lose some of it).

or, download unmult (free from red giant) which does all that in one step.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Darby Edelen
Re: Creating a Lens Flare with alpha ON TOP of another image -> Premiere
on Oct 25, 2013 at 9:21:24 pm

[Kevin Camp] "if you wanted to key it, i'd modify darby's recipe slightly and use the channel combiner effect, setting 'from' to max rgb and 'to' to alpha, then add the remove color matting effect.

this will keep all the color saturation (using shift channels will lose some of it)."


Good point. I always work in 32 bits per channel where that doesn't happen :)

Darby Edelen


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