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Alpha + RGB

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Spencer Tycksen
Alpha + RGB
on Nov 13, 2015 at 9:17:40 pm

I need help rendering out an alpha + RGB. I've created this little star animation that I need to render out as transparent. http://d.pr/i/oaa2

For my first attempt I used the Quicktime format with the animation video codec. The problem was when I went to put it on a background in Premiere after rendering it wasn't fully transparent. http://d.pr/i/qDXN

Whereas, if I had it on a background in after effects before rendering it, it looked fine. http://d.pr/i/1i1X9

I really need these as alphas. Any tips?

For reasons I don't feel like explaining, I'm operating in CS5.5.


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Walter Soyka
Re: Alpha + RGB
on Nov 13, 2015 at 9:49:33 pm

The problem is that part of the flare runs all the way out to the edges of the comp. In other words, that black background from your screenshot isn't truly black/transparent. Hover the mouse over the image in Ae, watch the Info panel, and I'm sure you'll see some non-zero alpha values.

Throw a soft round mask over the whole thing and your render will look cleaner.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Spencer Tycksen
Re: Alpha + RGB
on Nov 16, 2015 at 3:09:10 pm

Thanks for the reply. Do you know if there are other rendering options for rendering a high quality alpha besides quicktime animation? Also, I'm not clear on what you mean by putting a soft round mask on the whole thing. Could you clarify that? Thanks again for the input.


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Walter Soyka
Re: Alpha + RGB
on Nov 16, 2015 at 5:55:42 pm

[Spencer Tycksen] "Do you know if there are other rendering options for rendering a high quality alpha besides quicktime animation?"

Sure. There's CineForm on both platforms, there's ProRes 4444 on Mac. There's Avid's DNxHD, although I hesitate to recommend that unless you're specifically using Avid.

But the problem isn't the codec. It's that the image at the edges of your comp is not fully transparent, so when you put composite it over a larger image, you can see those edges, just like if you had a solid with full opacity there.


[Spencer Tycksen] "Also, I'm not clear on what you mean by putting a soft round mask on the whole thing. Could you clarify that?"

Sure -- precompose your Ae comp, then draw a mask around the flare shape, making sure to keep all the mask edges well inside the comp boundaries. Add a little bit of feathering to the mask, making sure again that you stay within the comp boundaries. You may need to slightly enlarge the comp and flare solids within the comp to give you enough room to work.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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