How do I integrate opencv as opencv_contrib for my JAVA project

[David-Braz]

How do I integrate opencv as opencv_contrib, I need to add the extra modules and use them in JAVA with the Intellij IDE, if you can give me step by step I will be very grateful, I have already managed to download opencv and opencv_contrib and I have already added the modules via cmake, then I compiled it through visual studio, but I don't know what to do after that, how do I import the library into my java project?

[joegeorge022]

Hopefully this helps....

1. Set Up Your OpenCV .dll File

• Find the opencv_java460.dll file (or the specific version you’re using) in your OpenCV build folder. It’s typically located in opencv/build/bin/Release/.
• Copy this .dll file to a convenient location, like C:\opencv_java.

2. Add OpenCV's Java Library (.jar) to IntelliJ

• Open IntelliJ and go to File > Project Structure > Libraries.
• Click the + button to add a new library, then locate and select the opencv-460.jar file (or your version) found in the opencv/build/java/ folder.

3. Tell IntelliJ Where to Find the .dll File

• In IntelliJ, go to Run > Edit Configurations.

• Under VM options, add the following line (adjust the path if necessary):

  -Djava.library.path=C:\opencv_java
  

  This line tells Java where to look for the opencv_java.dll file you copied earlier.

4. Test It Out

• Create a simple Java file to verify the OpenCV setup:

  import org.opencv.core.Core;
  
  public class OpenCVTest {
      static { System.loadLibrary(Core.NATIVE_LIBRARY_NAME); }
      
      public static void main(String[] args) {
          System.out.println("OpenCV version: " + Core.VERSION);
      }
  }

• Run this code. If it prints the OpenCV version, you’re all set!

5. Use opencv_contrib Modules

Since you've already included the extra modules when building, you can now use them in your Java project just like any other OpenCV feature.

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[David-Braz]

I managed to understand the part about importing the library, but my doubt is when I compiled opencv + opencv_contrib, it generated a new jar and dlls, but when I import it into Intellij it only recognizes the Jar as a Class, I go and I import the dll as Native Library to see if it works, but it doesn't work.

Would you have any suggestions? My main objective is to be able to integrate the modules extracted from opencv contrib to be able to use LBPHFaceRecognizer to train my facial recognition model.

Thank you for your attention.

[anonymous-leviathan]

Body

How do I integrate opencv as opencv_contrib, I need to add the extra modules and use them in JAVA with the Intellij IDE, if you can give me step by step I will be very grateful, I have already managed to download opencv and opencv_contrib and I have already added the modules via cmake, then I compiled it through visual studio, but I don't know what to do after that, how do I import the library into my java project?

Guidelines

• I have read and understood this category's guidelines before making this post.

To integrate opencv_contrib in your Java project using IntelliJ, after you’ve successfully built the libraries using CMake and Visual Studio, here’s a step-by-step guide to get things up and running:

1. Verify the Compiled Files

After building OpenCV with opencv_contrib modules, confirm that the compiled .dll (for Windows) or .so (for Linux/macOS) files were generated. These should be located in the build folder, usually under build/bin or build/lib.

2. Set Up Java Native Library Path

In your Java project, you'll need to tell Java where to find the OpenCV native libraries.

1. Locate the native library: Find the folder with the compiled .dll or .so files.
2. Set the library path: In IntelliJ, go to File > Project Structure > Modules. Then, in the Dependencies tab, add the path to the folder containing the native libraries as a VM option.
   • Example VM option: -Djava.library.path="path_to_opencv_build/lib"

3. Add OpenCV JAR to Your Project

1. Download the opencv-<version>.jar file if you haven’t done so already. This file should be in the build/bin directory, or you can find it from OpenCV releases online.
2. In IntelliJ, go to File > Project Structure > Libraries, click +, and add the opencv-<version>.jar to your project.

4. Load OpenCV in Your Java Code

In your Java code, load the native library by adding this line at the beginning of your program:

System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

Ensure Core.NATIVE_LIBRARY_NAME matches the library name. For OpenCV, it’s typically opencv_java<version>, where <version> corresponds to the version number you built.

5. Verify Your Setup

To check if everything is working, add a simple OpenCV code snippet in your project:

import org.opencv.core.Core;

public class Main {
    public static void main(String[] args) {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
        System.out.println("OpenCV loaded successfully");
    }
}

Run the code. If no errors are thrown and you see "OpenCV loaded successfully," then the setup is complete!

if your issue was fixed make this as a answer if it is not we can find more ways to that

[David-Braz]

I import the normal opencv library, but what do I do to import the opencv_contrib modules that I compiled with Visual Studio?

Thanks for your attention, it helps me a lot.

[anonymous-leviathan]

if your issue is fix make this as an answer if it is not we can discuss more