Digital Video Processing for Engineers

7

Alpha Blending

Chapter Outline

7.1 Introduction

7.2 Concept and Math Behind Alpha Blending

7.3 Implementing Alpha Blending in Hardware

7.4 Creating a Different Background

7.5 Conclusion

Alpha blending, or alpha compositing, is a video-processing technique that is used to combine two or more video streams on the same frame. This technique is increasingly used to overlay some graphics on a video, such as the 10-yard line in a football match or to put a different background behind a speaker.

We will learn how this is achieved and what kind of processing is required to overlay images.

7.1 Introduction

We will start with two images. Video consists of frames moving at a certain speed (30 fps or 60 fps) and we generally talk about processing within ...