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
Please understand that blend modes mix colors from overlapping objects together based on the brightness values within each color channel in an image. Every object 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 object that uses some of the channel’s color.
The effect that each blend mode has on overlapping objects 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 illustrated by the chart below.
For example, the Multiply blend mode renders transparent color values that fall into the white areas of an object, 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.