Creative Effects > Modular Keyer > Using Blend Nodes >
Blending the Front and Back Images of a Layer

There are two different methods you can use to blend the front and back images of a layer: Basic Blend and Curves Blend.

Basic Blend is appropriate for layers that do not have a matte component. It allows you to add the front and back images, and adjust the colour and opacity of the result image. In effect, since you are using the entire front image, the back image does not influence the result.

NoteBasic Blend is only available for MBlend nodes. It would not be useful to blend colour images in a composite in this way.

Curves Blend is suitable for layers that have a matte component. It allows you to use front and back matte curves to adjust the luminance of the front and back mattes, and also perform logical operations on the front and back images.

The two methods are mutually exclusive—you can set the blending in both the Basic Blend and Curves Blend menus, but it is the menu that is displayed that takes effect.

Basic Blend

Use Basic Blend to adjust the opacity and colour of an MBlend layer that has no matte component. This results in adding a second defined layer to the first one. You can control the opacity of the second layer.

NoteYou can also use Basic Blend when you have defined a matte in the Matte pipe. In this case, the blending is applied to the defined matte area only, rather than the entire front image.

To use Basic Blend:

1. Select the MBlend layer by clicking one of the blue boxes to the right of the layer.

   The MBlend menu appears and the name of the layer you selected appears in the Layer Name field.

   (a) Layer Name field(b) Blend box

   By default, if the layer does not have a matte component (that is, there are no nodes in the Matte pipe), the Basic Blend option is selected in the Blend box, and the Basic Blend controls are displayed at the right of the menu.

   NoteIf Curves Blend was previously selected, then it is displayed. To display Basic Blend, select it from the Blend box.
2. Display the Current Result view. This displays the result for the entire blend node.
3. Set the colour of the layer in the Colour field. A value of 100 sets the layer as white, a value of 0 sets it as black, and values in between give it a shade of grey.
4. Set the opacity of the layer in the Opacity field. A value of 100 makes the layer completely opaque, and a value of 0 makes it completely transparent.

Curves Blend

Use Curves Blend to adjust the blending of the front and back images of a CBlend or MBlend node layer that has a matte component.

To use Curves Blend:

1. Select the CBlend or MBlend layer by clicking the red or blue box to the right of the layer.

   The CBlend or MBlend menu appears and the name of the layer you selected appears in the Layer Name field.

   (a) Layer Name field(b) Blend box(c) Logic Ops box

   For MBlend nodes, if the layer has a matte component (that is, there are nodes in the Matte pipe), the Curves Blend option is selected in the Blend box and the Matte Curves graph is displayed at the right of the menu.

   NoteIf Basic Blend was previously selected, then it is displayed. To display Curves Blend, select it from the Blend box.
2. Display the Current Result view.

   This displays the result for the entire blend node.

3. To perform a logical operation on the front and back images, select one from the Logic Ops box.
4. Adjust the front and back matte curves as needed. See Adjusting the Front and Matte Luminance Curves.