How can you blend the pixels from multiple layers in After Effects?

Blending pixels from multiple layers in After Effects is primarily accomplished through the use of blend modes. Blend modes determine how the colors of a layer interact with the colors of the layers underneath it. By applying a blend mode, you can create various visual effects, such as darkening or lightening images, creating overlays, or enhancing textures, all based on the mathematical relationship between pixel values.

When you select a blend mode, the way your layer interacts with layers below it changes, allowing for creative outcomes that would be difficult to achieve with standard opacity adjustments alone. For instance, using a "Multiply" blend mode will darken the overall image by multiplying the color values of the top layer with those of the layers beneath it, creating a rich and layered appearance.

The other choices, while important in the layer management process, operate differently. Opacity settings affect the transparency of an individual layer but do not combine the visual characteristics of multiple layers in the same way blend modes do. Adjustment layers apply effects to all layers beneath them but do not influence the pixel blending themselves. Masks allow for selective visibility of layer areas but again do not blend colors across multiple layers as blend modes do.