How do I create a mask in Blender compositing?

Creating a mask in Blender compositing allows you to selectively apply effects to specific areas of your image. The following provides information on how to achieve this, based on the provided reference.

Mask Creation Process

Here's how to create a mask in Blender compositing:

1. Set up your nodes: Begin with your render layers and any effects nodes you want to apply. For example, in the provided reference, a glare node is being used.
2. Add a mask:
   • The reference video mentions creating a new window but does not describe a specific mask node.
   • Generally, you would add a mask node (such as a Ellipse Mask or a Rectangle Mask) node to your node tree.
3. Position the mask: Adjust the size and position of the mask to cover the area you want to be affected. For example, you might position an ellipse mask to cover the center of your image, as mentioned in the reference.
4. Connect the mask: Connect the output of your mask node to the factor input of a Mix node.
5. Connect the image and effect: Connect your original render layer to the upper input of the mix node, and the glare effect chain to the second mix node input.
6. Set the output: Connect the output of the mix node to the composite node.

This setup means that only the region covered by the mask will be affected by the glare effect, while the remaining area will retain the original image.

Example Scenario

Let's say you have an image and want to add a glare effect only to the central area, as described in the reference video. Here is how you could do that:

• Original image: Your rendered image is connected to a render layers node.
• Glare effect: A glare node adds a bloom effect to your render layers node.
• Mask: A mask node, is set to an ellipse that covers only the center of the image.
• Mix Node: A Mix Node combines the glare effect, masked using the mask node.
• Final Output: The final image with the masked glare effect is then connected to a composite node.

This means the glare will be visible only on the center, and the rest of the image will be untouched by the glare effect.

Key Takeaways

• Masks are used to control the areas that are affected by certain effects.
• You need to use a mix node to combine the masked effects with the original image.
• The factor input of the mix node determines where the second input effect will be applied.