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

Previewing and saving photos in CameraActivity


Our main activity, CameraActivity, needs to do the following:

  • On startup, use OpenCV Manager to ensure that the appropriate OpenCV shared libraries are available. (For more information about OpenCV Manager, refer back to the Building the OpenCV samples with Eclipse section in Chapter 1, Setting Up OpenCV.)

  • Display a live camera feed.

  • Provide the following menu actions:

    • Switch the active camera (for a device that has multiple cameras).

    • Save a photo and insert it into MediaStore so that it is accessible to apps such as Gallery. Immediately open the photo in LabActivity.

We will use OpenCV functionality wherever feasible, even though we could just use the standard Android libraries to display a live camera feed, save a photo, and so on.

OpenCV provides an abstract class called CameraBridgeViewBase, which represents a live camera feed. This class extends Android's SurfaceView class, so that its instances can be part of the view hierarchy. Moreover, a...