What is the most optimal way to create a "clipping" Grade layer that uses Set Matte and a Mask

LazarovLazarov Website User Posts: 57

You're probably familiar with the way of mask clipping in Photoshop. This makes a layer to be applied only within the boundaries of the base layer. You can apply masks to the clipped layer too. This is what I want to make in HitFilm.

The case is the following: I have two people filmed on a green screen, masked out and placed on a background. One of them has to cast shadow over a smaller area of the other one. Keep in mind I have about 15 layers with people, so the solution has to be as economic as possible. What I initially did was to create a Grade layer having:

1) Set Matte (with the layer of the person that will receive the shadow) with an Alpha mode (the person is a layer with a transparent background).

2) Levels Histogram or Curves that will create the shadow

+ a mask on that Grade layer that will limit the shadow only to a portion of the person.

Of course, that doesn't work as intended, because the Grade layer + Set Matte (with an Alpha matte) creates a black background outside the person's silhouette. The only workarounds I had were:

1) To use a blending mode on the Grade layer that will remove the black background. The problem is it will affect the way the shadow looks as colors and contrast and I have to fight with it to make it look as if the blending mode were "Normal"

2) To duplicate the person layer, add the shadow and a mask to constrain it over a certain area. The problem here is that if I make changes in the original layer (such as tweaking the exposure or the colors) I have to remember to always copy the settings over the shadow layer. This makes the rendering way slower too. This is why I prefer the 1st workaround although it's not perfect either.

Is there a way to do that with my initial intent and approach, but maybe I am missing a minute detail?



  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,219 Ambassador

    You're almost there. Look in your Set Matte and change the Alpha from Replace to Subtract, then Invert the mask. After that, it should work as intended. 

    Don't use Histogram. Hitfilm's Levels Histogram reads back from its own output to generate and draw the Histogram in its interface--even when the tab is closed. This gives Levels Histogram overhead that will add up over 15 layers. Use Curves. Alternatively, try Gamma or Fill Color and adjust Opacity.

  • LazarovLazarov Website User Posts: 57
    edited April 2019

    Thanks for the reply @Triem23. However, the solution is not working. I have already tried it, but I anyway made an attempt following those instructions. It has a black background around the cutout unless I change the blending mode of the Grade to something different from "Normal," which has the drawbacks I described above and "works" with Set Matte set to Alpha + Replace and Invert is unchecked.

    Here's a look at the Grade layer that's added above the layer with the blond lady where the shadow has to fall onto:


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