Simple question. I want to cross dissolve between two almost identical, mostly white layers. A title is fading on. Yet, in linear mode, when i opacity from 100 to 0 on one layer and from 0 to 100 on the other layer, I am getting a dip in density, i.e. the white fades down a little bit during the dissolve. The keyframes are in linear. Fixed areas are specified as hold frames.
If I pull the bezier handles to get a logarithmic curve, it more or less smooths out the dissolve. Still, that shouldn't be necessary! Why is this simple operation of a cross dissolve a pain in the neck and what am I doing wrong?
thank you very much
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That's because AE doesn't do a simple addition of the opacity values. Try changing your background color to a bright red and you should see part of it. The trick is to ensure that at least one layer is at 100% opacity, then dissolve on the other layer over this.
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[John Graves]"Still, that shouldn't be necessary! Why is this simple operation of a cross dissolve a pain in the neck and what am I doing wrong?"
It's a common issue with AE newbies. If you do as Rholand suggests and add a layer under your white layers, you will see the bottom layer become visible during that's because at the middle of the dissolve, both layers are at about 50% opacity. That doesn't add up to 100%, it means you can see through both.
To perform a dissolve in AE, you need to think of it as a change in opacity on the upper most layer from 0-100 or 100-0%. That will either reveal or completely obscure the underlying layers.
Just pre-compose the two layers you are cross-fading and set the blending mode on the top layer to "Alpha Add". In the pre-comp you will still see the dip, but in the main comp where this cross-fading comp is nested the cross-fade will appear correctly with no dip.