Is there a way to invert keyframes?

[Filip Vandueren]

My 2 €¢s :

if you have keyframes setup, and their interpolation is not linear,
you may be in for a surprise if you only invert the value of the keyframe.

You’ll also have to invert the Velocity precentages in the “Keyframe Velocities dialog”,

so that may amount to 18 values you have to alter manually for ‘just 6 Keyframes’

I would use an inverting expression, in this case: 100-value.
Check out the difference in the curves (the red one is the result of the expression):

[Filip Vandueren]

That would be the same as “keyframe assistants -> reverse keyframes”
You would be inverting their timing, not their value.

[Peter O’connell]

Try this, select your layer and press command + d to copy it. Remove all the keyframes from the new layer. Alt click the opacity of the new layer to create an expression for opacity. The expression should look (except for the layer name) like this:

thisComp.layer(“theOtherLayersName”).opacity * -1 +100

Turn off the visibility of the original layer.
That should do the trick.
Good luck
Pete