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How to create a simple perfect crossfade in AE

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John WayneHow to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 7:37:26 pm

Hello,

a very simple question for my first post but I cannot manage to find the solution:

I want to fade two very similar footages (or still images) that include alpha blur around.
Of course, I tried to make it work with opacity and "blend" effect. That works but leaves me unsatisfied about the quality.

Do you guys see what I mean? Did you find a way to crossfade perfectly 2 images with alpha (and alpha blur)?

Thanks a lot.


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Dave LaRondeRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 8:18:42 pm

[John Wayne] "work with opacity and "blend" effect. That works but leaves me unsatisfied about the quality."

Geez, Duke, what's the problem with the quality? Can you describe what's wrong? I've used both with great success.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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John WayneRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 8:26:32 pm

Thanks for your prompt repply.

When you crossfade 2 blury objects with alpha that are very similar (the edges are the same), at one point, both have a 50% opacity making the crossfade unusable.

My other choice is to make image 2 fade in over image 1 and then fade out image 1 but then I have my blur duplicated...

I know it sound very dumb but I have to crossfade these 2 images.

Do you see what I mean?


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Walter SoykaRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 8:54:50 pm

[John Wayne] "When you crossfade 2 blury objects with alpha that are very similar (the edges are the same), at one point, both have a 50% opacity making the crossfade unusable. My other choice is to make image 2 fade in over image 1 and then fade out image 1 but then I have my blur duplicated..."

Pre-comp the two layers in question, and apply the blur the pre-comp (instead of duplicating it on each layer). Instead of cross-fading the layers within the precomp, fade one in or out over the other.

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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Dave LaRondeRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 8:56:24 pm

By their very nature, blurs are going to be semi-transparent. Thus, if the positons of the two layers and amount of their blurs don't precisely match, as you reduce the opacity of one, there will be a little see-through to the other. I don't see how it can be avoided.

Now, we ARE talking about dissolving from one layer to another, right?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kevin CampRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 9:08:22 pm

it's unclear where the blur is coming from... are the images already blurred prior to ae, or is the blur being done in ae?

if the blur is in ae, then i think walter's suggestion would work.

also, if there is only these two layers that need to fade between, then the blend effect should work, but the blur would be placed after the blend effect - you could still do it with many layers, but you'd need a blend effect for each dissolve, at that point i think it would be easier to use walter's pre-comp method and keyframe assistant>sequence layers...

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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John WayneRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 9:18:38 pm

Thanks for your replies.

My problem is that the image sequences come from a 3D program already blured (just on some parts as you can imagine).

I understand that it is mathematics, and all this is "normal". I am still hoping there is a magical solution :D

In the worst case, I can make very long crossfades or play with the opacity curves to make it less visible.


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Kevin CampRe: How to create a simple perfect crossfade in AE
by on Mar 16, 2011 at 9:48:36 pm

i think the blend effect should work... make sure you turn off (hide) the the layer the is set as 'blend with layer' in the effect -- you only need to see the layer that the effect is applied to.

another option would be to try and remove the alphas, do the dissolve, then apply the alpha back on.

you could try the set channels effect, setting the 'set alpha source' to 'full' for both layers, which should give you some rather ugly edges. then dissolve one on the other. then duplicate one layer, remove the set channels effect, move it on top of the other two layers and set the blending mode to 'stencil alpha'. this obviously effects the alpha of all layers bellow it, so you may need to precomp those layers.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Walter SoykaRe: How to create a simple perfect crossfade in AE
by on Mar 17, 2011 at 2:45:16 pm

You could also create three precomps: one for the outgoing image in the dissolve, one for the incoming image, and one of the entire background.

Add the background precomp as the bottom layer to both the outgoing and incoming image precomps.

Now a simple dissolve out of the outgoing over the incoming other should be clean.

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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Hadrien DiboreRe: How to create a simple perfect crossfade in AE
by on Mar 17, 2011 at 6:55:32 pm

I will try that,

Thanks!


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