Java OpenCV from Maven

Question

Is there any way to get OpenCV from repository? Which artifact should I add to pom.xml? Every tutorial I\'d found is from \'14 and it seems like something chang

Answer 1

All you need: install jar in local maven repository with:

mvn install:install-file -Dfile=C:\opencv411\build\java\opencv-411.jar -DgroupId=org -DartifactId=opencv -Dversion=4.1.1 -Dpackaging=jar

create a dependency in pom.xml:

 <dependency> 
 <groupId>org</groupId> 
 <artifactId>opencv</artifactId>
 <version>4.1.1</version>  
</dependency> 

Now that jar is on, we need to somehow add the OpenCV libraries. I did this by adding the lib folder in java.library.path to the maven-surefire plugin:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-surefire-plugin</artifactId>
 <version>2.22.2</version>
 <configuration>
  <argLine>-Djava.library.path=${project.build.outputDirectory}/lib</argLine>
 </configuration>
</plugin>

    public static void main(String[] arges) throws MalformedURLException, 
IOException, Exception {
    loadLibraries();

    // create and print on screen a 3x3 identity matrix
    System.out.println("Create a 3x3 identity matrix...");
    Mat mat = Mat.eye(3, 3, CvType.CV_8UC1);
    System.out.println("mat = " + mat.dump());

    // prepare to convert a RGB image in gray scale
    String location = "resources/Poli.jpg";
    System.out.print("Convert the image at " + location + " in gray scale... ");
    // get the jpeg image from the internal resource folder
    Mat image = Imgcodecs.imread(location);
    // convert the image in gray scale
    Imgproc.cvtColor(image, image, Imgproc.COLOR_RGB2GRAY);
    // write the new image on disk
    Imgcodecs.imwrite("resources/Poli-gray.jpg", image);
    System.out.println("Done!");

}

    private static void loadLibraries() {

    try {
        InputStream in = null;
        File fileOut = null;
        String osName = System.getProperty("os.name");
//            String opencvpath = System.getProperty("user.dir");
        String opencvpath = "C:\\opencv411\\build\\java\\";
        if (osName.startsWith("Windows")) {
            int bitness = Integer.parseInt(System.getProperty("sun.arch.data.model"));
            if (bitness == 32) {
                opencvpath = opencvpath + "\\x86\\";
            } else if (bitness == 64) {
                opencvpath = opencvpath + "\\x64\\";
            } else {
                opencvpath = opencvpath + "\\x86\\";
            }
        } else if (osName.equals("Mac OS X")) {
            opencvpath = opencvpath + "Your path to .dylib";
        }
        System.out.println(opencvpath);
//        System.out.println("Core.NATIVE_LIBRARY_NAME = " + Core.NATIVE_LIBRARY_NAME);
        System.out.println("Core.NATIVE_LIBRARY_NAME = " + "opencv_java411.dll");
//        System.load(opencvpath + Core.NATIVE_LIBRARY_NAME + ".dll");
        System.load(opencvpath + "opencv_java411.dll");
    } catch (Exception e) {
        throw new RuntimeException("Failed to load opencv native library", e);
    }
}

Answer 2

For windows there was a problem with @Sachin Aryal's answer. The answer by @Anirban Chakraborty is a very good hint. But, there was still issues at runtime as described in this thread.

Finally replacing OpenCV.loadShared(); with OpenCV.loadLocally(); worked for me.

Answer 3

Add the following dependency in your POM file:

<dependency>
    <groupId>org.openpnp</groupId>
    <artifactId>opencv</artifactId>
    <version>3.2.0-0</version>
</dependency>

and replace the following lines:

System.loadLibrary(Core.NATIVE_LIBRARY_NAME)

with

nu.pattern.OpenCV.loadShared();

This should solve the problem in WINDOWS also. Happy Coding.

Answer 4

This worked for me.

nu.pattern.OpenCV.loadLibrary();

I'm using following maven dependency

<dependency>
  <groupId>nu.pattern</groupId>
  <artifactId>opencv</artifactId>
  <version>2.4.9-4</version>
</dependency>

Answer 5

Just use it nu.pattern.OpenCV.loadShared();

write a class with this static void method

class Test {
public static void loadOpenCVNativeLibrary() {
nu.pattern.OpenCV.loadShared();
}
}

and after call it in your application class (with static main) for web application (spring boot for example) like this

static {
Test.loadOpenCVNativeLibrary();
}
...
public static void main(String[] args) throws UnknownHostException {
}

Answer 6

Try this, see if it works:

• nu.pattern.OpenCV.loadShared();
• System.loadLibrary(org.opencv.core.Core.NATIVE_LIBRARY_NAME);

More info here in API section: https://github.com/patternconsulting/opencv

Also have 2.4.9-7 opencv dependency.