Apple Motion 2 - Manual (Page 249)

Chapter 3 Basic Compositing 249
Using Blend Modes
Each of the available blend modes presents a different method for combining two or
more images together. Blend modes work in addition to an object’s alpha channel and
opacity parameter.
How Blend Modes Affect Images
To understand the descriptions of each blend mode in this section, it’s important to
understand that blend modes mix colors from overlapping images together based on
the brightness values within each color channel in an image. Every image consists of
red, green, blue, and alpha channels. Each individual channel contains a range of
brightness values that define the intensity of each pixel in the image that uses some of
that color.
The effect that each blend mode has on objects that overlap in the Canvas depends on
the range of color values within each object. The red, green, and blue channels within
each overlapping pixel are mathematically combined to yield the final image.
These value ranges can be described as blacks, midrange values, or whites. These
regions are loosely illustrated by the chart below.
For example, the Multiply blend mode renders color values that fall into the white areas
of an image transparent, while the black areas of the image are left alone. All midrange
color values become translucent, with colors falling into the lighter end of the scale
becoming more transparent than the colors that fall into the darker end of the scale.
Layer Blend Modes
Blend modes work differently depending on whether they’re used with layers or
objects. In particular, the Combine blend mode is only available for layers.
Blacks Whites Midrange color values
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