Opacity setting bleeds to lower layers

[Jim1587]

I’m trying to create a scene where a ghost walks through a room of people. The ghost isn’t a member of the group in the room. I shot a ‘clean plate’ video of the room with people. A 2nd clip was shot with the to-be-ghosted person walking through the empty room. The camera was tripod mounted and not moved between shots. In Premiere, the ‘clean plate’ clip is placed below the ‘ghost’ clip. The opacity of the ‘ghost’ layer is set to 50%. As expected, the ghost-person becomes semi-transparent. But so does everyone on the layer below – even though that layer opacity remains at 100%. I’ve tried reversing the stacking order and have tried all the listed blend modes. Neither resolved the issue. I’m using Premiere Pro v24.6.1 on a Windows 10 pc. The Premiere Pro System Compatibility Report shows no conflicts. Any thoughts on how to prevent opacity settings from bleeding onto lower layers?

[Ann Bens]

Please post screenshots of timeline and Effect Controls with all parameters showing.

[Jim1587]

[Hutch Harris]

Hi @Jim1587 - so what is happening is your "living people" clip on track 1 is definitely at 100% opacity, but the background of the clean plate on track 2 is making that entire image appear to be 50% transparent.

Try changing the Blend Mode on your "ghost" layer (track 2) to Darken.

EDIT: You could also keyframe the opacity to go from 0% to 50% if you want the ghost to fade in/out of reality 😉

[Jim1587]

Hutch – thanks for taking the time to look at this! The Darken Blend mode did make the dark pixels darker, but left a degree of transparency on lighter pixels (e.g. skin, etc) of the ‘solid’ people. I tried duplicating the layer and applying Darken to both. It didn’t help. I tried all of the other listed blend modes. No love there. I added a Transform effect to an Adjustment layer. I tried it with opacity set to 100%, placed above the ‘clean plate’ clip. I also tried a 50% opacity Adjustment layer above the ‘ghost’ layer. I tried rearranging the stacking order in various ways.

 It didn’t help. Do you know of any way to limit opacity to a single layer? Masking?

[PaulMurphy · Accepted solution]

This is expected behavior. Blending a layer on top of another at 50% opacity will blend both layers, regardless of what’s in the frame.

You’ll need to mask the ghost in the top layer so that only a specific area of the frame is being blended with the bottom layer.

[R Neil Haugen · Accepted solution]

Paul has it right ... you have to mask the 'ghost', excluding everything else on their layer. Or it will also be at 50% overlay. Premiere may do well enough for your needs, or you may find it better Q and actually quicker to rotoscope in AfterEffects.

This is why this is so often done with green/blue screen shooting for the 'ghost' element. Quickly drops out the screen then so there's less work in masking in the ghost.

[Christian.Z · Accepted solution]

There is no issue here, this is normal behaviour.
you see when changing the opacity to 50% of your ghost, its not only your ghost that is semi-transparent, but the entire room, causing the people lower layer to only be 50% visible as well.
There are 3 ways to approach this:

1- when filming all your elements, including people should be present in both plate and ghost shots. only variable between 2 shots should be the ghost.

2- The above might prove tricky since it will be difficult to have people stay the same way. Masking and/or rotoscoping your ghost is the way to go.

3- Try to play around with opacity modes.

4- (Bonus) if it was me, I would do both masking and opacity mode on the ghost. should give a pretty interesting look 

[Jim1587]

Thanks to everyone who responded! Each response was a learning opportunity. Rotoscoping in After Effects provided what I needed. I was impressed with After Effect’s tracking ability.