Layer blending overview
While the Opacity parameter defines a uniform level of transparency for a layer, the blend modes allow you many more creative options to control how the overlapping images interact, based on the colors in each layer. By default, each layer’s blend mode is set to Normal, so changes to a layer’s opacity uniformly affect every part of the image equally.
Blend modes can create transparency in a layer regardless of the setting of its Opacity parameter. This is because the pixels of an image with a selected blend mode are combined with the pixels of any layers lying immediately below in the Canvas. For example, if you overlap two layers, then set the blend mode of the top one to Screen, the darker areas of the screened image become transparent, while the lighter areas remain more solid, resulting in the following image:
Important: The transparency created by most of the available blend modes only affects how a layer combines with overlapping layers underneath. These blend modes do nothing to affect a layer’s alpha channel. For information about blend modes that do affect a layer’s alpha channel, see Blend modes that manipulate alpha channels.
Each blend mode combines layers in different ways. For example, setting the top layer’s blend mode to Multiply yields a result opposite to that of the Screen blend mode, as the darker areas of the image remain solid, and the lighter areas become transparent.
Blend modes only affect the combination of a layer with the layers below it. Any layers appearing above have no effect on this interaction, even if the layer is transparent. In the following example, the text layers on the top level have no effect on the blended images below.
For overlapping layers with different blend modes, the bottommost pair of layers is combined first, and that combination then interacts with the next layer up, and so on until all overlapping layers are combined for the final image. In this case, each layer with a specified blend mode only interacts with the image below it, whether that image is a single layer or a pair of layers blended together.
Each of Motion’s blend modes works in conjunction with the Opacity parameter to alter the interaction between the foreground and background layers. Adjusting a layer’s opacity lessens the blending effect assigned to it, even as it reduces that layer’s visibility, allowing you to customize any blend mode to better suit your needs.
Blend modes only affect overlapping layers, and have no interaction with your project’s background color (unless the background is set to Environment). If you specify a blend mode for a layer that doesn’t overlap anything, that layer remains as it was before.