Keylight and Masks Workflow Avoid Spill

Report · Mar 26, 2023

I am trying to key out a green sock that has two distinct shades of green. Can someone send me in the right direction re: how to apply Keylight to both areas?

I know I need to use masks, the pen tool, and pre-comps, but not sure the order I should do it in. Also wondering if the two masks will spill into eachother and create a problematic Key?

Report · Mar 26, 2023

That key is going to be problematic either way because plain and simply it's not the right key color. this is a situation where you wouldn't even bother with creating a direct key. Rather you'd create separate mattes in two pre-comps and then combine them to be used in the parent comp. That also eliminates any obscure masking procedures outside the crudest holdout matte (inner/ outer mask in Keylight).

Mylenium

Report · Mar 26, 2023

I made a screenshot of your screenshot, named the file original footage, imported it into AE, Created a Main Comp from the footage, duplicated the footage layer twice, and added a bright yellow solid, so I could clearly see how well the matte works, then added Keylight to the top copy of the original footage. I sampled the color of the sock just to the left of the shadow, spun down the minimum properties in Keylight that always need adjustment, Looked at Combined matte, and fiddled with the matte until I had a solid white background and mostly black background. That took about 2 minutes.

I then turned off the top layer and did the same thing with Layer 2, but I sampled just to the right of the shadow to generate a combined matte that is very good on the lighter side of the matte. I had the info Panel open so I could verify that I had full white and full black the matte. I'll take care of the gray areas in the next step using the Multiply blend mode.

The next step is to turn on Layer 1, set the Blend mode to Multiply, check the matte for holes using the Info Panel, Pre-compose Layer 1 and 2, name the Pre-comp Track Matte, then set the Track Matte Pre-comp as a Luma Track matte for the original footage.

That's how to handle poorly lit greenscreen projects easily. I do it all the time. You can fine-tune the matte and fix the edge spill by adding Keylight to the Original footage, temporarily turning off the track matte, then pulling a decent key and using Keylight to correct the edge contamination and colors. You don't worry much about how well the sock is keyed out in this step; you just want to correct the spill, then turn on the Track Matte again. If needed you use more copies of the layer and the Track Matte to create light wrap and do further color corrections to sell the background replacement.

Report · Mar 26, 2023

Copy you, thank you, Rick! You're blowing my mind!

Report · Mar 27, 2023

Hi Richard,

I attached a screenshot of where I'm at. I ended up having to export the clip from Premiere and importing it into AE. But I think my issue is with Dynamic Link.

I am going to start fresh with a full rez clip next weekend. But when I get it all set up again correctly, how will I actually dissappear the sock? Is that a blend mode thing?

Report · Mar 27, 2023

Set the matte layer as a Luma Track Matte for the original footage. The bottom GIF shows the workflow.

The sock turns yellow because there is a yellow solid below the sock.

If you want to fill the hole you'll need to have the appropriate camera movement and use Content Aware Fill or save a frame as a Photoshop file and create a background without the sock. The most efficient workflow depends on what happens in the original shot.

Report · Mar 28, 2023

Ok gotcha. So I will need to do the bottom GIF workflow and then replace the yellow solid layer with the background Still.

The shot is attached.

I definitely have to get Photoshop then, because there's a second shot in this that's going to be even more complicated I fear.

Report · Apr 18, 2023

@Rick Gerard - "If you want to fill the hole you'll need to have the appropriate camera movement and use Content Aware Fill or save a frame as a Photoshop file and create a background without the sock. The most efficient workflow depends on what happens in the original shot. "

Can you explain this in more detail?

Report · Apr 18, 2023

Every shot is different in some way. If you want to fill the hole created when you make a hole where the green sock is keyed out, you'll need some pixels that match the background.

The easiest way to fill that hole is to find a frame where the sock is not there, then start building the clean plate. This is where it is often a good idea to stabilize motion so the background does not move. You can then take a frame or two as Photoshop Files and start creating a clean plate - an image with no foot in the shot. You place that image below the keyed layer so the hole is filled with actual pixels.

Then you put the motion back in the original shot and add the motion to the clean plate.

If I saw this shot instead of just a frame of it, I could give you the complete workflow. Maybe this tutorial I did will help you figure something out. I used a graphic to replace the bench; you would use a clean plate made from your frame grabs of the original shot.

This is nothing new. My friend Scott Squires shows the matte creation and clean plate workflow in these tutorials from about 15 years ago. The basics are the same. Make a hole, and fill it. Track if you can or time shift. I did similar things by painting masks on acetate by hand and layering 35mm film in an optical printer one frame at a time.

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Report · Apr 18, 2023

Thank you, Rick. Yes - I am catching up to the pros here. Appreciate all the resources.

Should I build the clean plate in Photoshop or After Effects? And the two frames I would build it from would be a begninning frame without the sock and an end frame without the sock, correct?