Alpha Compositing Modes

Alpha compositing is a technique that allows combining multiple layers of transparent images or video into a single composite image.

Alpha compositing modes define how the transparency information in two or more images is combined to produce the final result.

Some common alpha compositing modes include Over, In, Out, Atop, XOR, and various mathematical blend modes like Multiply and Screen.

The Over mode combines the transparency of the foreground image with the background image while preserving the color information of both.

The In mode takes the transparency of the foreground image and clips it to the shape of the background image, resulting in a transparent region outside the shape of the background.

The Out mode takes the inverted transparency of the foreground image and clips it to the shape of the background image, resulting in a transparent region inside the shape of the background.

The Atop mode combines the transparency of the foreground image with the background image but clips it to the shape of the background, resulting in a transparent region outside that shape.

The XOR mode combines the transparency of the foreground image with the background image, but it excludes the region where both images are transparent or opaque.

Mathematical blend modes, such as Multiply and Screen, use formulas that combine color and transparency information based on mathematical operations like multiplication or addition.

An example of using alpha compositing is overlaying a semi-transparent image with another image to create a visual effect like a watermark or a drop shadow.