Opencv级联分类器实现人脸识别

在本章中，我们将学习如何使用OpenCV使用系统相机捕获帧。org.opencv.videoio包的VideoCapture类包含使用相机捕获视频的类和方法。让我们一步一步学习如何捕捉帧 -

第1步：加载OpenCV本机库

在使用OpenCV库编写Java代码时，您需要做的第一步是使用loadLibrary（）加载OpenCV的本机库。加载OpenCV本机库，如下所示。

// Loading the core library
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

第2步：实例化视频捕获类

使用前面本教程中提到的任何函数来实例化Mat类。

// Instantiating the VideoCapture class (camera:: 0)
VideoCapture capture = new VideoCapture(0);

第3步：读取帧

您可以使用VideoCapture类的read（）方法从相机中读取帧。此方法接受Mat类的对象来存储读取的帧。

// Reading the next video frame from the camera
Mat matrix = new Mat();
capture.read(matrix);

代码：

 package com.gitee.dgw.Camera;

 import javafx.application.Application;
 import javafx.embed.swing.SwingFXUtils;
 import javafx.scene.Group;
 import javafx.scene.Scene;
 import javafx.scene.image.ImageView;
 import javafx.scene.image.WritableImage;
 import javafx.stage.Stage;
 import org.opencv.core.Mat;
 import org.opencv.imgcodecs.Imgcodecs;
 import org.opencv.videoio.VideoCapture;

 import java.awt.image.BufferedImage;
 import java.awt.image.DataBufferByte;
 import java.awt.image.WritableRaster;

 public class CameraSnapshotJavaFX extends Application {

    static {
       platformUtils.loadLibraries();
    }
    Mat matrix = null;

    @Override
    public void start(Stage stage) {
       // Capturing the snapshot from the camera
       CameraSnapshotJavaFX obj = new CameraSnapshotJavaFX();
       WritableImage writableImage = obj.capureSnapShot();

       // Saving the image
       obj.saveImage();

       // Setting the image view
       ImageView imageView = new ImageView(writableImage);

       // setting the fit height and width of the image view
       imageView.setFitHeight(400);
       imageView.setFitWidth(600);

       // Setting the preserve ratio of the image view
       imageView.setPreserveRatio(true);

       // Creating a Group object
       Group root = new Group(imageView);

       // Creating a scene object
       Scene scene = new Scene(root, 600, 400);

       // Setting title to the Stage
       stage.setTitle("Capturing an image");

       // Adding scene to the stage
       stage.setScene(scene);

       // Displaying the contents of the stage
       stage.show();
    }
    public WritableImage capureSnapShot() {
       WritableImage WritableImage = null;

       // Instantiating the VideoCapture class (camera:: 0)
       VideoCapture capture = new VideoCapture(0);

       // Reading the next video frame from the camera
       Mat matrix = new Mat();
       capture.read(matrix);

       // If camera is opened
       if( capture.isOpened()) {
          // If there is next video frame
          if (capture.read(matrix)) {
             // Creating BuffredImage from the matrix
             BufferedImage image = new BufferedImage(matrix.width(),
                matrix.height(), BufferedImage.TYPE_3BYTE_BGR);

             WritableRaster raster = image.getRaster();
             DataBufferByte dataBuffer = (DataBufferByte) raster.getDataBuffer();
             byte[] data = dataBuffer.getData();
             matrix.get(0, 0, data);
             this.matrix = matrix;

             // Creating the Writable Image
             WritableImage = SwingFXUtils.toFXImage(image, null);
          }
       }
       return WritableImage;
    }
    public void saveImage() {
       // Saving the Image
       String file = "z://sanpshot.jpg";

       // Instantiating the imgcodecs class
       Imgcodecs imageCodecs = new Imgcodecs();

       // Saving it again
       imageCodecs.imwrite(file, matrix);
    }
    public static void main(String args[]) {
       launch(args);
    }
 }