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);
}
}