In this tutorial, I will show you how to use Blender to replace a green screen from a still image and create a final composite for your project.
Removing the Green Screen
I am using photos that I downloaded from Pexels – links are in the description
It is important that both images are the same size or the final composite will be clipped to the smallest size
If you are using Pexels, use the dropdown menu next to the download button to download a custom size image if needed
In my case, I needed to change the background image to 4000 x 6000 to match the green screen image
Open the Compositing Workspace
Open the Output Properties tab and change the Resolution to the size of your image (in this case, 4000 x 6000)
Activate “Use Nodes”
Drag in each image individually into the Compositing Workspace
Select the Render Layer node and delete it
Use SHIFT + A to open the Add menu
Under the Output menu, choose the Viewer node so we can see the image as we are working on it
Connect the green screen image to both the Composite node and the Viewer node
Using the V-key, you can zoom out to see the entire image
Use SHIFT + Right-click and drag over the two Noodles to merge the image connection to the nodes
Use Shift + A to open the Add menu
Under the Matte menu, choose the Keying node and place it between the Image node and the two output nodes
Select the Key Color
Use the Eyedropper to select a midtone green from the background
Connect the Matte output of the Keying node to the two output nodes
Change the White and Black values as needed to get as clean of a background as possible
Also, use the Dilute Erode option to further clean up the background
Reconnect the Image output to the two output nodes
Adding a Background
For the background add an Alpha Over node (found under the Add menu and Color menu) between the Keying node and the two output nodes
Connect the green screen image to the bottom Image input of the Alpha Over node
Connect the background image to the top Image input of the Alpha Over node
Rendering
To render the image, choose Render Image under the Render menu
Under the Image menu, you can Save the image