Book Image

Android Application Programming with OpenCV

By : Joseph Howse
Book Image

Android Application Programming with OpenCV

By: Joseph Howse

Overview of this book

Take a smartphone from your pocket, and within a few seconds, you can snap a photo, manipulate it, and share it with the world. You have just achieved mass production of image data. With a computer vision library such as OpenCV, you can analyze and transform copious amounts of image data in real time on a mobile device. The upshot to this is that you, as developers, can provide mobile users with many new kinds of images, constantly highlighting certain visual features that are of artistic or practical interest. Android is a convenient platform for such experiments because it uses a high-level language (Java), it provides standardized interfaces for sharing image data between applications, and it is mostly open source, so everyone can study its implementation. Android Application Programming with OpenCV is a practical, hands-on guide that covers the fundamental tasks of computer vision—capturing, filtering, and analyzing images-with step-by-step instructions for writing both an application and reusable library classes. Android Application Programming with OpenCV looks at OpenCV's Java bindings for Android and dispels mysteries such as which version of these bindings to use, how to integrate with standard Android functionality for layout, event handling, and data sharing, and how to integrate with OpenGL for rendering. By following the clear, concise, and modular examples provided in this book, you will develop an application that previews, captures, and shares photos with special effects based on color manipulation, edge detection, image tracking, and 3D rendering.Beneath the application layer, you will develop a small but extensible library that you can reuse in your future projects. This library will include filters for selectively modifying an image based on edge detection, 2D and 3D image trackers, and adapters to convert the Android system's camera specifications into OpenCV and OpenGL projection matrices. If you want a quick start in computer vision for Android, then this is the book for you. By the end of Android Application Programming with OpenCV, you will have developed a computer vision application that integrates OpenCV, Android SDK, and OpenGL.
Table of Contents (12 chapters)
Android Application Programming with OpenCV
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Building projection matrices in CameraProjectionAdapter


Here is an exercise for sightseers. Choose a famous photo that was taken at a recognizable location, somewhere that should still look similar today. Travel to that site and explore it until you know how the photographer set up the shot. Where was the camera positioned and how was it rotated?

If you found an answer, and if you are sure of it, you must have already known which lens or zoom setting the photographer used. Without that information, you could not have narrowed down the feasible camera poses to the one, true pose.

We face a similar problem when trying to determine the pose of a photographed object relative to a monocular (single-lens) camera. To find a unique solution, we first need to know the camera's horizontal and vertical field of view, and horizontal and vertical resolution in pixels.

Fortunately, we can get these data via the android.hardware.Camera.Parameters class. Our CameraProjectionAdapter class will allow client...