A Simple Way to Utilise Luma Mattes in After Effects

There are numerous ways to manipulate and apply effects to objects or certain parts of your shot when using After Effects. Many of those methods, however, can be very cumbersome and time-consuming. That’s why in today’s After Effects tutorial Ruan of Tunnel Vizion explores much simpler and straightforward technique that will let you manipulate various objects in your shots without the need to apply intense rotoscoping and complex keying techniques. From changing colour of an object to applying multiple effects and everything in between you can integrate this method in your After Effects workflow whenever you need to get quick and efficient results.

Once you import your clip in After Effects, make sure you duplicate it by pressing Ctrl + D before you move on further. Rename the copied clip and by right-clicking navigate to Effect>Keying and select Keylight 1.2.  In this particular case, Ruan decides to modify the look of the red poker chip in the frame. He just selects the Color Picker next to the Screen Color in the Keylight Effect control panel and then samples a color from the object’s surface.


Furthermore, to better tweak the Matte, you can change the View Mode from Source to Combine Matte. This step of the process will visualize the Matte that you are creating. If you’d like to invert the colours of your Matte you can do so by either applying the Invert Effect to your clip or you can just modify the Clip Black and Clip White settings under Screen Matte and set those to 100 and 0 respectively. Additionally, you can fine-tune your Matte by tweaking the latter along with Screen Balance in the Keylight Effects panel.


If you still have some spill in other areas of your shot, you can draw a mask around the object that you want to focus on. With the Matte layer selected, navigate to Rectangle Mask and draw a quick mask. Use the tracker if there’s any movement involved in your shot. Finally, when you have created the perfect mask you can add an Adjustment Layer and place it right below your Matte clip. Then change the Track Matte of the Adjustment layer from None to Luma Matte. This way After Effects will utilise the brightness of the object that can be now modified further.


The final step of the process is to add an effect to the Adjustment layer that should affect only the object below the matte that you’ve just created. Now you can stylise the look of this object or change its colour, or do whatever you want. Simply use your creativity along with this simple and effective After Effects technique everytime you need to enhance your project further.

[source: TunnelvizionTV]

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