如何在Android中使用OpenCV

Get the OpenCV package for Android development¶

1. Go to the http://sourceforge.net/projects/opencvlibrary/files/opencv-android/ and download the latest available version. Currently it is OpenCV-2.3.1-android-bin.tar.bz2 ....當初沒抓,搞了很久,因為Download OpenCV-2.3.1-win-superpack.exe (131.1 MB).下載這個版本沒有提供.project
2. Create new folder for Android+OpenCV development.
   

   Note
   Better to use a path without spaces in it. Otherwise you will probably have problems with ndk-build.

3. Unpack the OpenCV package into that dir.
   You can unpack it using any popular archiver (for example with 7-Zip):
   
   
   On Unix you can also use the following command:
   

   tar -jxvf ~/Downloads/OpenCV-2.3.1-android-bin.tar.bz2
   

   For this tutorial I have unpacked OpenCV to the C:\Work\android-opencv\ directory.

Open OpenCV library and samples in Eclipse¶

1. Start the Eclipse and choose your workspace location.
   I recommend to start familiarizing yourself with OpenCV for Android from a new clean workspace. So I have chosen my OpenCV package directory for the new workspace:
   

   

2. Configure your ADT plugin
   Important
   ADT plugin settings are workspace-dependent. So you have to repeat this step each time when you create a new workspace.
   Once you have created a new workspace, you have to point the ADT plugin to the Android SDK directory. This setting is stored in workspace metadata, as result this step is required each time when you are creating new workspace for Android development. See Configuring the ADT Plugin document for the original instructions from Google.
   
   • Select Window ‣ Preferences... to open the Preferences panel (Mac OS X: Eclipse ‣ Preferences):
   • 
   • Select Android from the left panel.

   You may see a dialog asking whether you want to send usage statistics to Google. If so, make your choice and click Proceed. You cannot continue with this procedure until you click Proceed.

   • For the SDK Location in the main panel, click Browse... and locate your Android SDK directory.
   • Click Apply button at the bottom right corner of main panel:
   • Click OK to close preferences dialog.
3. Import OpenCV and samples into workspace.
   OpenCV library is packed as a ready-for-use Android Library Project. You can simply reference it in your projects.
   Each sample included into OpenCV-2.3.1-android-bin.tar.bz2 is a regular Android project that already references OpenCV library. Follow next steps to import OpenCV and samples into workspace:
   
   • Right click on the Package Explorer window and choose Import... option from the context menu:
   • In the main panel select General ‣ Existing Projects into Workspace and press Next button:
   • For the Select root directory in the main panel locate your OpenCV package folder. (If you have created workspace in the package directory, then just click Browse... button and instantly close directory choosing dialog with OK button!) Eclipse should automatically locate OpenCV library and samples:
   • Click Finish button to complete the import operation.
   After clicking Finish button Eclipse will load all selected projects into workspace. And... will indicate numerous errors:
   

   

   However all these errors are only false-alarms!
   To help Eclipse to understand that there are no any errors choose OpenCV library in Package Explorer (left mouse click) and press F5 button on your keyboard. Then choose any sample (except first samples in Tutorial Base and Tutorial Advanced) and also press F5.
   After this manipulation Eclipse will rebuild your workspace and error icons will disappear one after another:
   

   

   Once Eclipse completes build you will have the clean workspace without any build errors:
   

   

   Note
   If you are importing only OpenCV library without samples then instead of second refresh command (F5) you might need to make Android Tools ‣ Fix Project Properties from project context menu.

Running OpenCV Samples¶

At this point you should be able to build and run all samples except two from Advanced tutorial (these samples require Android NDK to build working applications, see the next tutorial Using C++ OpenCV code with Android binary package to learn how to compile them).
Also I want to note that only Tutorial 1 Basic - 0. Android Camera and Tutorial 1 Basic - 1. Add OpenCV samples are able to run on Emulator from Android SDK. Other samples are using OpenCV Native Camera which does not work with emulator.
Note
Latest Android SDK tools, revision 12 can run ARM v7 OS images but Google does not provide such images with SDK.
Well, running samples from Eclipse is very simple:

• Connect your device with adb tool from Android SDK or create Emulator with camera support.
  

  • See Managing Virtual Devices document for help with Android Emulator.
    
  • See Using Hardware Devices for help with real devices (not emulators).

• Select project you want to start in Package Explorer:guilabel: and just press Ctrl + F11 or select option Run ‣ Run from main menu, or click Run button on the toolbar.
  Note
  Android Emulator can take several minutes to start. So, please, be patient.
• On the first run Eclipse will ask you how to run your application:
  
• Select the Android Application option and click OK button. Eclipse will install and run the sample.
  Here is Tutorial 1 Basic - 1. Add OpenCV sample detecting edges using Canny algorithm from OpenCV:
  

How to use OpenCV library project in your application¶

If you already have an Android application, you can add a reference to OpenCV and import all its functionality.

1. First of all you need to have both projects (your app and OpenCV) in a single workspace. So, open workspace with your application and import the OpenCV project into your workspace as stated above.
2. Add a reference to OpenCV project.
   Do the right mouse click on your app in Package Explorer, go to Properties ‣ Android ‣ Library ‣ Addand choose the OpenCV library project.