Merge pull request #301 from emchristiansen:javasample2.4

doc/tutorials/definitions/tocDefinitions.rst

@@ -8,4 +8,5 @@
 .. |Author_FernandoI| unicode:: Fernando U+0020 Iglesias U+0020 Garc U+00ED a
 .. |Author_EduardF| unicode:: Eduard U+0020 Feicho
 .. |Author_AlexB| unicode:: Alexandre U+0020 Benoit
-
+.. |Author_EricCh| unicode:: Eric U+0020 Christiansen
+.. |Author_AndreyP| unicode:: Andrey U+0020 Pavlenko

doc/tutorials/introduction/desktop_java/java_dev_intro.rst

@@ -0,0 +1,523 @@
+
+.. _Java_Dev_Intro:
+
+
+Introduction to Java Development
+********************************
+
+Last updated: 12 February, 2013.
+
+As of OpenCV 2.4.4, OpenCV supports desktop Java development using nearly the same interface as for
+Android development. This guide will help you to create your first Java (or Scala) application using OpenCV.
+We will use either `Eclipse <http://eclipse.org/>`_, `Apache Ant <http://ant.apache.org/>`_ or the
+`Simple Build Tool (SBT) <http://www.scala-sbt.org/>`_ to build the application.
+
+For further reading after this guide, look at the :ref:`Android_Dev_Intro` tutorials.
+
+What we'll do in this guide
+***************************
+
+In this guide, we will:
+
+* Get OpenCV with desktop Java support
+
+* Create an ``Ant``, ``Eclipse`` or ``SBT`` project
+
+* Write a simple OpenCV application in Java or Scala
+
+The same process was used to create the samples in the :file:`samples/java` folder of the OpenCV repository,
+so consult those files if you get lost.
+
+Get OpenCV with desktop Java support
+************************************
+
+Starting from version 2.4.4 OpenCV includes desktop Java bindings.
+The most simple way to get it is downloading the appropriate package of **version 2.4.4 or higher** from the
+`OpenCV SourceForge repository <http://sourceforge.net/projects/opencvlibrary/files/>`_.
+
+.. note:: Windows users can find the prebuilt files needed for Java development in the
+          :file:`opencv/build/java/` folder inside the package.
+          For other OSes it's required to build OpenCV from sources.
+
+Another option to get OpenCV sources is to clone `OpenCV git repository
+<https://github.com/Itseez/opencv/>`_.
+In order to build OpenCV with Java bindings you need :abbr:`JDK (Java Development Kit)`
+(we recommend `Oracle/Sun JDK 6 or 7 <http://www.oracle.com/technetwork/java/javase/downloads/>`_),
+`Apache Ant <http://ant.apache.org/>`_ and `Python` v2.6 or higher to be installed.
+
+Build OpenCV
+############
+
+Let's build OpenCV:
+
+        .. code-block:: bash
+
+           git clone git://github.com/Itseez/opencv.git
+           cd opencv
+           git checkout 2.4
+           mkdir build
+           cd build
+
+Generate a Makefile or a MS Visual Studio* solution, or whatever you use for
+building executables in your system:
+
+        .. code-block:: bash
+
+           cmake -DBUILD_SHARED_LIBS=OFF ..
+
+or
+
+        .. code-block:: bat
+
+           cmake -DBUILD_SHARED_LIBS=OFF -G "Visual Studio 10" ..
+
+.. note:: When OpenCV is built as a set of **static** libraries (``-DBUILD_SHARED_LIBS=OFF`` option)
+          the Java bindings dynamic library is all-sufficient,
+          i.e. doesn't depend on other OpenCV libs, but includes all the OpenCV code inside.
+
+Examine the output of CMake and ensure ``java`` is one of the modules "To be built".
+If not, it's likely you're missing a dependency. You should troubleshoot by looking
+through the CMake output for any Java-related tools that aren't found and installing them.
+
+     .. image:: images/cmake_output.png
+        :alt: CMake output
+        :align: center
+
+Now start the build:
+
+        .. code-block:: bash
+
+           make -j8
+
+or
+
+        .. code-block:: bat
+
+           msbuild /m OpenCV.sln /t:Build /p:Configuration=Release /v:m
+
+Besides all this will create a ``jar`` containing the Java interface (:file:`bin/opencv_2.4.4.jar`)
+and a native dynamic library containing Java bindings and all the OpenCV stuff
+(:file:`bin/Release/opencv_java244.dll` or :file:`bin/libopencv_java244.so` respectively).
+We'll use these files later.
+
+Create a simple Java sample and an Ant build file for it
+********************************************************
+
+.. note::
+    The described sample is provided with OpenCV library in the :file:`opencv/samples/java/ant` folder.
+
+* Create a folder where you'll develop this sample application.
+
+* In this folder create an XML file with the following content using any text editor:
+
+    .. code-block:: xml
+        :linenos:
+
+        <project name="SimpleSample" basedir="." default="rebuild-run">
+
+            <property name="src.dir"     value="src"/>
+
+            <property name="lib.dir"     value="${ocvJarDir}"/>
+            <path id="classpath">
+                <fileset dir="${lib.dir}" includes="**/*.jar"/>
+            </path>
+
+            <property name="build.dir"   value="build"/>
+            <property name="classes.dir" value="${build.dir}/classes"/>
+            <property name="jar.dir"     value="${build.dir}/jar"/>
+
+            <property name="main-class"  value="${ant.project.name}"/>
+
+
+            <target name="clean">
+                <delete dir="${build.dir}"/>
+            </target>
+
+            <target name="compile">
+                <mkdir dir="${classes.dir}"/>
+                <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="classpath"/>
+            </target>
+
+            <target name="jar" depends="compile">
+                <mkdir dir="${jar.dir}"/>
+                <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">
+                    <manifest>
+                        <attribute name="Main-Class" value="${main-class}"/>
+                    </manifest>
+                </jar>
+            </target>
+
+            <target name="run" depends="jar">
+                <java fork="true" classname="${main-class}">
+                    <sysproperty key="java.library.path" path="${ocvLibDir}"/>
+                    <classpath>
+                        <path refid="classpath"/>
+                        <path location="${jar.dir}/${ant.project.name}.jar"/>
+                    </classpath>
+                </java>
+            </target>
+
+            <target name="rebuild" depends="clean,jar"/>
+
+            <target name="rebuild-run" depends="clean,run"/>
+
+        </project>
+
+    .. note::
+        This XML file can be reused for building other Java applications.
+        It describes a common folder structure in the lines 3 - 12 and common targets
+        for compiling and running the application.
+
+        When reusing this XML don't forget to modify the project name in the line 1,
+        that is also the name of the `main` class (line 14).
+        The paths to OpenCV `jar` and `jni lib` are expected as parameters
+        (``"${ocvJarDir}"`` in line 5 and ``"${ocvLibDir}"`` in line 37), but
+        you can hardcode these paths for your convenience.
+        See `Ant documentation <http://ant.apache.org/manual/>`_ for detailed description
+        of its build file format.
+
+* Create an :file:`src` folder next to the :file:`build.xml` file and a :file:`SimpleSample.java` file in it.
+
+* Put the following Java code into the :file:`SimpleSample.java` file:
+    .. code-block:: java
+
+        import org.opencv.core.Mat;
+        import org.opencv.core.CvType;
+        import org.opencv.core.Scalar;
+
+        class SimpleSample {
+
+          static{ System.loadLibrary("opencv_java244"); }
+
+          public static void main(String[] args) {
+            Mat m = new Mat(5, 10, CvType.CV_8UC1, new Scalar(0));
+            System.out.println("OpenCV Mat: " + m);
+            Mat mr1 = m.row(1);
+            mr1.setTo(new Scalar(1));
+            Mat mc5 = m.col(5);
+            mc5.setTo(new Scalar(5));
+            System.out.println("OpenCV Mat data:\n" + m.dump());
+          }
+
+        }
+
+* Run the following command in console in the folder containing :file:`build.xml`:
+    .. code-block:: bash
+
+        ant -DocvJarDir=path/to/dir/containing/opencv-244.jar -DocvLibDir=path/to/dir/containing/opencv_java244/native/library
+
+    For example:
+
+    .. code-block:: bat
+
+        ant -DocvJarDir=X:\opencv-2.4.4\bin -DocvLibDir=X:\opencv-2.4.4\bin\Release
+
+    The command should initiate [re]building and running the sample.
+    You should see on the screen something like this:
+
+    .. image:: images/ant_output.png
+        :alt: run app with Ant
+        :align: center
+
+Create a simple Java project in Eclipse
+***************************************
+
+Now let's look at the possiblity of using OpenCV in Java when developing in Eclipse IDE.
+
+* Create a new Eclipse workspace
+* Create a new Java project via :guilabel:`File --> New --> Java Project`
+
+    .. image:: images/eclipse_new_java_prj.png
+        :alt: Eclipse: new Java project
+        :align: center
+
+    Call it say "HelloCV".
+
+* Open :guilabel:`Java Build Path` tab on :guilabel:`Project Properties` dialog
+    and configure additional library (OpenCV) reference (jar and native library location):
+
+    .. image:: images/eclipse_user_lib.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib2.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib3.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib4.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib5.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib6.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib7.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+    .. image:: images/eclipse_user_lib8.png
+        :alt: Eclipse: external JAR
+        :align: center
+
+   ` `
+
+* Add a new Java class (say ``Main``) containing the application entry:
+
+    .. image:: images/eclipse_main_class.png
+        :alt: Eclipse: Main class
+        :align: center
+
+* Put some simple OpenCV calls there, e.g.:
+    .. code-block:: java
+
+        import org.opencv.core.CvType;
+        import org.opencv.core.Mat;
+
+        public class Main {
+            public static void main(String[] args) {
+                System.loadLibrary("opencv_java244");
+                Mat m  = Mat.eye(3, 3, CvType.CV_8UC1);
+                System.out.println("m = " + m.dump());
+            }
+        }
+
+* Press :guilabel:`Run` button and find the identity matrix content in the Eclipse ``Console`` window.
+
+    .. image:: images/eclipse_run.png
+        :alt: Eclipse: run
+        :align: center
+
+Create an SBT project and samples in Java and Scala
+***************************************************
+
+Now we'll create a simple Java application using SBT. This serves as a brief introduction to
+those unfamiliar with this build tool. We're using SBT because it is particularly easy and powerful.
+
+First, download and install `SBT <http://www.scala-sbt.org/>`_ using the instructions on its `web site <http://www.scala-sbt.org/>`_.
+
+Next, navigate to a new directory where you'd like the application source to live (outside :file:`opencv` dir).
+Let's call it "JavaSample" and create a directory for it:
+
+        .. code-block:: bash
+
+           cd <somewhere outside opencv>
+           mkdir JavaSample
+
+Now we will create the necessary folders and an SBT project:
+
+        .. code-block:: bash
+
+           cd JavaSample
+           mkdir -p src/main/java # This is where SBT expects to find Java sources
+           mkdir project # This is where the build definitions live
+
+Now open :file:`project/build.scala` in your favorite editor and paste the following.
+It defines your project:
+
+        .. code-block:: scala
+
+            import sbt._
+            import Keys._
+
+           object JavaSampleBuild extends Build {
+             def scalaSettings = Seq(
+               scalaVersion := "2.10.0",
+               scalacOptions ++= Seq(
+                 "-optimize",
+                 "-unchecked",
+                 "-deprecation"
+               )
+             )
+
+             def buildSettings =
+               Project.defaultSettings ++
+               scalaSettings
+
+             lazy val root = {
+               val settings = buildSettings ++ Seq(name := "JavaSample")
+               Project(id = "JavaSample", base = file("."), settings = settings)
+             }
+           }
+
+Now edit :file:`project/plugins.sbt` and paste the following.
+This will enable auto-generation of an Eclipse project:
+
+        .. code-block:: scala
+
+           addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.1.0")
+
+Now run ``sbt`` from the :file:`JavaSample` root and from within SBT run ``eclipse`` to generate an eclipse project:
+
+        .. code-block:: bash
+
+           sbt # Starts the sbt console
+           > eclipse # Running "eclipse" from within the sbt console
+
+You should see something like this:
+
+     .. image:: images/sbt_eclipse.png
+        :alt: SBT output
+        :align: center
+
+You can now import the SBT project to Eclipse using :guilabel:`Import ... -> Existing projects into workspace`.
+Whether you actually do this is optional for the guide;
+we'll be using SBT to build the project, so if you choose to use Eclipse it will just serve as a text editor.
+
+To test that everything is working, create a simple "Hello OpenCV" application.
+Do this by creating a file :file:`src/main/java/HelloOpenCV.java` with the following contents:
+
+        .. code-block:: java
+
+            public class HelloOpenCV {
+              public static void main(String[] args) {
+                System.out.println("Hello, OpenCV");
+             }
+           }
+
+Now execute ``run`` from the sbt console, or more concisely, run ``sbt run`` from the command line:
+
+        .. code-block:: bash
+
+           sbt run
+
+You should see something like this:
+
+     .. image:: images/sbt_run.png
+        :alt: SBT run
+        :align: center
+
+Copy the OpenCV jar and write a simple application
+********************************************************
+
+Now we'll create a simple face detection application using OpenCV.
+
+First, create a :file:`lib/` folder and copy the OpenCV jar into it.
+By default, SBT adds jars in the lib folder to the Java library search path.
+You can optionally rerun ``sbt eclipse`` to update your Eclipse project.
+
+        .. code-block:: bash
+
+           mkdir lib
+           cp <opencv_dir>/build/bin/opencv_<version>.jar lib/
+           sbt eclipse
+
+Next, create the directory src/main/resources and download this Lena image into it:
+
+     .. image:: images/lena.png
+        :alt: Lena
+        :align: center
+
+Make sure it's called :file:`"lena.png"`.
+Items in the resources directory are available to the Java application at runtime.
+
+Next, copy :file:`lbpcascade_frontalface.xml` from :file:`opencv/data/` into the :file:`resources`
+directory:
+
+        .. code-block:: bash
+
+           cp <opencv_dir>/data/lbpcascades/lbpcascade_frontalface.xml src/main/resources/
+
+Now modify src/main/java/HelloOpenCV.java so it contains the following Java code:
+
+.. code-block:: java
+
+   import org.opencv.core.Core;
+   import org.opencv.core.Mat;
+   import org.opencv.core.MatOfRect;
+   import org.opencv.core.Point;
+   import org.opencv.core.Rect;
+   import org.opencv.core.Scalar;
+   import org.opencv.highgui.Highgui;
+   import org.opencv.objdetect.CascadeClassifier;
+
+   //
+   // Detects faces in an image, draws boxes around them, and writes the results
+   // to "faceDetection.png".
+   //
+   class DetectFaceDemo {
+     public void run() {
+       System.out.println("\nRunning DetectFaceDemo");
+
+       // Create a face detector from the cascade file in the resources
+       // directory.
+       CascadeClassifier faceDetector = new CascadeClassifier(getClass().getResource("/lbpcascade_frontalface.xml").getPath());
+       Mat image = Highgui.imread(getClass().getResource("/lena.png").getPath());
+
+       // Detect faces in the image.
+       // MatOfRect is a special container class for Rect.
+       MatOfRect faceDetections = new MatOfRect();
+       faceDetector.detectMultiScale(image, faceDetections);
+
+       System.out.println(String.format("Detected %s faces", faceDetections.toArray().length));
+
+       // Draw a bounding box around each face.
+       for (Rect rect : faceDetections.toArray()) {
+           Core.rectangle(image, new Point(rect.x, rect.y), new Point(rect.x + rect.width, rect.y + rect.height), new Scalar(0, 255, 0));
+       }
+
+       // Save the visualized detection.
+       String filename = "faceDetection.png";
+       System.out.println(String.format("Writing %s", filename));
+       Highgui.imwrite(filename, image);
+     }
+   }
+
+   public class HelloOpenCV {
+     public static void main(String[] args) {
+       System.out.println("Hello, OpenCV");
+
+       // Load the native library.
+       System.loadLibrary("opencv_java244");
+       new DetectFaceDemo().run();
+     }
+   }
+
+Note the call to ``System.loadLibrary("opencv_java244")``.
+This command must be executed exactly once per Java process prior to using any native OpenCV methods.
+If you don't call it, you will get ``UnsatisfiedLink errors``.
+You will also get errors if you try to load OpenCV when it has already been loaded.
+
+Now run the face detection app using ``sbt run``:
+
+        .. code-block:: bash
+
+           sbt run
+
+You should see something like this:
+
+     .. image:: images/sbt_run_face.png
+        :alt: SBT run
+        :align: center
+
+It should also write the following image to :file:`faceDetection.png`:
+
+     .. image:: images/faceDetection.png
+        :alt: Detected face
+        :align: center
+
+You're done!
+Now you have a sample Java application working with OpenCV, so you can start the work on your own.
+We wish you good luck and many years of joyful life!

doc/tutorials/introduction/table_of_content_introduction/table_of_content_introduction.rst

@@ -101,6 +101,26 @@ Here you can read tutorials about how to set up your computer to work with the O
                       :height: 90pt
                       :width:  90pt
 
+* **Desktop Java**
+
+  .. tabularcolumns:: m{100pt} m{300pt}
+  .. cssclass:: toctableopencv
+
+  ================ =================================================
+  |JavaLogo|       **Title:** :ref:`Java_Dev_Intro`
+
+                   *Compatibility:* > OpenCV 2.4.4
+
+                   *Authors:* |Author_EricCh| and |Author_AndreyP|
+
+                   Explains how to build and run a simple desktop Java application using Eclipse, Ant or the Simple Build Tool (SBT).
+
+  ================ =================================================
+
+     .. |JavaLogo| image:: images/Java_logo.png
+                        :height: 90pt
+                        :width:  90pt
+
 * **Android**
 
   .. tabularcolumns:: m{100pt} m{300pt}
@@ -238,10 +258,11 @@ Here you can read tutorials about how to set up your computer to work with the O
    ../linux_eclipse/linux_eclipse
    ../windows_install/windows_install
    ../windows_visual_studio_Opencv/windows_visual_studio_Opencv
+   ../desktop_java/java_dev_intro
    ../android_binary_package/android_dev_intro
    ../android_binary_package/O4A_SDK
    ../android_binary_package/dev_with_OCV_on_Android
    ../ios_install/ios_install
    ../display_image/display_image
    ../load_save_image/load_save_image
-   ../how_to_write_a_tutorial/how_to_write_a_tutorial
+   ../how_to_write_a_tutorial/how_to_write_a_tutorial

samples/java/ant/build.xml

@@ -0,0 +1,49 @@
+<project name="SimpleSample" basedir="." default="rebuild-run">
+
+    <property name="src.dir"     value="src"/>
+
+    <property name="lib.dir"     value="${ocvJarDir}"/>
+    <path id="classpath">
+        <fileset dir="${lib.dir}" includes="**/*.jar"/>
+    </path>
+
+    <property name="build.dir"   value="build"/>
+    <property name="classes.dir" value="${build.dir}/classes"/>
+    <property name="jar.dir"     value="${build.dir}/jar"/>
+
+    <property name="main-class"  value="${ant.project.name}"/>
+
+
+    <target name="clean">
+        <delete dir="${build.dir}"/>
+    </target>
+
+    <target name="compile">
+        <mkdir dir="${classes.dir}"/>
+        <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="classpath"/>
+    </target>
+
+    <target name="jar" depends="compile">
+        <mkdir dir="${jar.dir}"/>
+        <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">
+            <manifest>
+                <attribute name="Main-Class" value="${main-class}"/>
+            </manifest>
+        </jar>
+    </target>
+
+    <target name="run" depends="jar">
+        <java fork="true" classname="${main-class}">
+            <sysproperty key="java.library.path" path="${ocvLibDir}"/>
+            <classpath>
+                <path refid="classpath"/>
+                <path location="${jar.dir}/${ant.project.name}.jar"/>
+            </classpath>
+        </java>
+    </target>
+
+    <target name="rebuild" depends="clean,jar"/>
+
+    <target name="rebuild-run" depends="clean,run"/>
+
+</project>

samples/java/ant/src/SimpleSample.java

@@ -0,0 +1,19 @@
+import org.opencv.core.Mat;
+import org.opencv.core.CvType;
+import org.opencv.core.Scalar;
+
+class SimpleSample {
+
+  static{ System.loadLibrary("opencv_java244"); }
+
+  public static void main(String[] args) {
+    Mat m = new Mat(5, 10, CvType.CV_8UC1, new Scalar(0));
+    System.out.println("OpenCV Mat: " + m);
+    Mat mr1 = m.row(1);
+    mr1.setTo(new Scalar(1));
+    Mat mc5 = m.col(5);
+    mc5.setTo(new Scalar(5));
+    System.out.println("OpenCV Mat data:\n" + m.dump());
+  }
+
+}

samples/java/eclipse/HelloCV/.classpath

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.USER_LIBRARY/opencv-2.4.4"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

samples/java/eclipse/HelloCV/.project

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>HelloCV</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

samples/java/eclipse/HelloCV/.settings/org.eclipse.jdt.core.prefs

@@ -0,0 +1,11 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.7
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=1.7
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.source=1.7

samples/java/eclipse/HelloCV/src/Main.java

@@ -0,0 +1,12 @@
+import org.opencv.core.CvType;
+import org.opencv.core.Mat;
+
+public class Main {
+
+    public static void main(String[] args) {
+        System.loadLibrary("opencv_java244");
+        Mat m  = Mat.eye(3, 3, CvType.CV_8UC1);
+        System.out.println("m = " + m.dump());
+    }
+
+}

samples/java/sbt/README

@@ -0,0 +1,13 @@
+A demo of the Java wrapper for OpenCV with two examples:
+1) feature detection and matching and
+2) face detection.
+The examples are coded in Scala and Java.
+Anyone familiar with Java should be able to read the Scala examples.
+Please feel free to contribute code examples in Scala or Java, or any JVM language.
+
+To run the examples:
+1) Install OpenCV and copy the OpenCV jar to lib/.
+   This jar must match the native libraries installed in your system.
+   If this isn't the case, you may get a java.lang.UnsatisfiedLinkError at runtime.
+2) Go to the root directory and type "sbt/sbt run".
+   This should generate images in your current directory.

samples/java/sbt/project/build.scala

@@ -0,0 +1,22 @@
+import sbt._
+import Keys._
+
+object OpenCVJavaDemoBuild extends Build {
+  def scalaSettings = Seq(
+    scalaVersion := "2.10.0",
+    scalacOptions ++= Seq(
+      "-optimize",
+      "-unchecked",
+      "-deprecation"
+    )
+  )
+
+  def buildSettings =
+    Project.defaultSettings ++
+    scalaSettings
+
+  lazy val root = {
+    val settings = buildSettings ++ Seq(name := "OpenCVJavaDemo")
+    Project(id = "OpenCVJavaDemo", base = file("."), settings = settings)
+  }
+}

samples/java/sbt/project/plugins.sbt

@@ -0,0 +1 @@
+addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.1.0")

samples/java/sbt/sbt/sbt

@@ -0,0 +1 @@
+java -Xms512M -Xmx1536M -Xss1M -XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=384M -jar `dirname $0`/sbt-launch.jar "$@"

samples/java/sbt/src/main/java/DetectFaceDemo.java

@@ -0,0 +1,44 @@
+import org.opencv.core.Core;
+import org.opencv.core.Mat;
+import org.opencv.core.MatOfRect;
+import org.opencv.core.Point;
+import org.opencv.core.Rect;
+import org.opencv.core.Scalar;
+import org.opencv.highgui.Highgui;
+import org.opencv.objdetect.CascadeClassifier;
+
+/*
+ * Detects faces in an image, draws boxes around them, and writes the results
+ * to "faceDetection.png".
+ */
+public class DetectFaceDemo {
+    public void run() {
+        System.out.println("\nRunning DetectFaceDemo");
+
+        // Create a face detector from the cascade file in the resources
+        // directory.
+        CascadeClassifier faceDetector = new CascadeClassifier(getClass()
+                .getResource("/lbpcascade_frontalface.xml").getPath());
+        Mat image = Highgui.imread(getClass().getResource(
+                "/AverageMaleFace.jpg").getPath());
+
+        // Detect faces in the image.
+        // MatOfRect is a special container class for Rect.
+        MatOfRect faceDetections = new MatOfRect();
+        faceDetector.detectMultiScale(image, faceDetections);
+
+        System.out.println(String.format("Detected %s faces",
+                faceDetections.toArray().length));
+
+        // Draw a bounding box around each face.
+        for (Rect rect : faceDetections.toArray()) {
+            Core.rectangle(image, new Point(rect.x, rect.y), new Point(rect.x
+                    + rect.width, rect.y + rect.height), new Scalar(0, 255, 0));
+        }
+
+        // Save the visualized detection.
+        String filename = "faceDetection.png";
+        System.out.println(String.format("Writing %s", filename));
+        Highgui.imwrite(filename, image);
+    }
+}

samples/java/sbt/src/main/scala/Main.scala

@@ -0,0 +1,20 @@
+/*
+ * The main runner for the Java demos.
+ * Demos whose name begins with "Scala" are written in the Scala language,
+ * demonstrating the generic nature of the interface.
+ * The other demos are in Java.
+ * Currently, all demos are run, sequentially.
+ *
+ * You're invited to submit your own examples, in any JVM language of
+ * your choosing so long as you can get them to build.
+ */
+object Main extends App {
+  // We must load the native library before using any OpenCV functions.
+  // You must load this library _exactly once_ per Java invocation.
+  // If you load it more than once, you will get a java.lang.UnsatisfiedLinkError.
+  System.loadLibrary("opencv_java")
+
+  ScalaCorrespondenceMatchingDemo.run()
+  ScalaDetectFaceDemo.run()
+  new DetectFaceDemo().run()
+}

samples/java/sbt/src/main/scala/ScalaCorrespondenceMatchingDemo.scala

@@ -0,0 +1,69 @@
+import org.opencv.highgui.Highgui
+import org.opencv.features2d.DescriptorExtractor
+import org.opencv.features2d.Features2d
+import org.opencv.core.MatOfKeyPoint
+import org.opencv.core.Mat
+import org.opencv.features2d.FeatureDetector
+import org.opencv.features2d.DescriptorMatcher
+import org.opencv.core.MatOfDMatch
+import reflect._
+
+/*
+ * Finds corresponding points between a pair of images using local descriptors.
+ * The correspondences are visualized in the image "scalaCorrespondences.png",
+ * which is written to disk.
+ */
+object ScalaCorrespondenceMatchingDemo {
+  def run() {
+    println(s"\nRunning ${classTag[this.type].toString.replace("$", "")}")
+
+    // Detects keypoints and extracts descriptors in a given image of type Mat.
+    def detectAndExtract(mat: Mat) = {
+      // A special container class for KeyPoint.
+      val keyPoints = new MatOfKeyPoint
+      // We're using the SURF detector.
+      val detector = FeatureDetector.create(FeatureDetector.SURF)
+      detector.detect(mat, keyPoints)
+
+      println(s"There were ${keyPoints.toArray.size} KeyPoints detected")
+
+      // Let's just use the best KeyPoints.
+      val sorted = keyPoints.toArray.sortBy(_.response).reverse.take(50)
+      // There isn't a constructor that takes Array[KeyPoint], so we unpack
+      // the array and use the constructor that can take any number of
+      // arguments.
+      val bestKeyPoints: MatOfKeyPoint = new MatOfKeyPoint(sorted: _*)
+
+      // We're using the SURF descriptor.
+      val extractor = DescriptorExtractor.create(DescriptorExtractor.SURF)
+      val descriptors = new Mat
+      extractor.compute(mat, bestKeyPoints, descriptors)
+
+      println(s"${descriptors.rows} descriptors were extracted, each with dimension ${descriptors.cols}")
+
+      (bestKeyPoints, descriptors)
+    }
+
+    // Load the images from the |resources| directory.
+    val leftImage = Highgui.imread(getClass.getResource("/img1.png").getPath)
+    val rightImage = Highgui.imread(getClass.getResource("/img2.png").getPath)
+
+    // Detect KeyPoints and extract descriptors.
+    val (leftKeyPoints, leftDescriptors) = detectAndExtract(leftImage)
+    val (rightKeyPoints, rightDescriptors) = detectAndExtract(rightImage)
+
+    // Match the descriptors.
+    val matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE)
+    // A special container class for DMatch.
+    val dmatches = new MatOfDMatch
+    // The backticks are because "match" is a keyword in Scala.
+    matcher.`match`(leftDescriptors, rightDescriptors, dmatches)
+
+    // Visualize the matches and save the visualization.
+    val correspondenceImage = new Mat
+    Features2d.drawMatches(leftImage, leftKeyPoints, rightImage, rightKeyPoints, dmatches, correspondenceImage)
+    val filename = "scalaCorrespondences.png"
+    println(s"Writing ${filename}")
+    assert(Highgui.imwrite(filename, correspondenceImage))
+  }
+}

samples/java/sbt/src/main/scala/ScalaDetectFaceDemo.scala

@@ -0,0 +1,43 @@
+import org.opencv.core.Core
+import org.opencv.core.MatOfRect
+import org.opencv.core.Point
+import org.opencv.core.Scalar
+import org.opencv.highgui.Highgui
+import org.opencv.objdetect.CascadeClassifier
+import reflect._
+
+/*
+ * Detects faces in an image, draws boxes around them, and writes the results
+ * to "scalaFaceDetection.png".
+ */
+object ScalaDetectFaceDemo {
+  def run() {
+    println(s"\nRunning ${classTag[this.type].toString.replace("$", "")}")
+
+    // Create a face detector from the cascade file in the resources directory.
+    val faceDetector = new CascadeClassifier(getClass.getResource("/lbpcascade_frontalface.xml").getPath)
+    val image = Highgui.imread(getClass.getResource("/AverageMaleFace.jpg").getPath)
+
+    // Detect faces in the image.
+    // MatOfRect is a special container class for Rect.
+    val faceDetections = new MatOfRect
+    faceDetector.detectMultiScale(image, faceDetections)
+
+    println(s"Detected ${faceDetections.toArray.size} faces")
+
+    // Draw a bounding box around each face.
+    for (rect <- faceDetections.toArray) {
+      Core.rectangle(
+        image,
+        new Point(rect.x, rect.y),
+        new Point(rect.x + rect.width,
+          rect.y + rect.height),
+        new Scalar(0, 255, 0))
+    }
+
+    // Save the visualized detection.
+    val filename = "scalaFaceDetection.png"
+    println(s"Writing ${filename}")
+    assert(Highgui.imwrite(filename, image))
+  }
+}