- OpenCV - GUI
- OpenCV - Writing an Image
- OpenCV - Reading Images
- OpenCV - Storing Images
- OpenCV - Environment
- OpenCV - Overview
- OpenCV - Home
Types of Images
Image Conversion
Drawing Functions
- OpenCV - Adding Text
- OpenCV - Drawing Arrowed Lines
- OpenCV - Drawing Convex Polylines
- OpenCV - Drawing Polylines
- OpenCV - Drawing an Ellipse
- OpenCV - Drawing a Rectangle
- OpenCV - Drawing a Line
- OpenCV - Drawing a Circle
Blur
Filtering
- OpenCV - Image Pyramids
- OpenCV - Morphological Operations
- OpenCV - Erosion
- OpenCV - Dilation
- OpenCV - Filter2D
- OpenCV - SQRBox Filter
- OpenCV - Box Filter
- OpenCV - Bilateral Filter
Thresholding
Sobel Derivatives
Transformation Operations
Camera and Face Detection
Geometric Transformations
Miscellaneous Chapters
OpenCV Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
OpenCV - Using Camera
In this chapter, we will learn how to use OpenCV to capture frames using the system camera. The VideoCapture class of the org.opencv.videoio package contains classes and methods to capture video using the camera. Let’s go step by step and learn how to capture frames −
Step 1: Load the OpenCV native pbrary
While writing Java code using OpenCV pbrary, the first step you need to do is to load the native pbrary of OpenCV using the loadLibrary(). Load the OpenCV native pbrary as shown below.
// Loading the core pbrary System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Step 2: Instantiate the video capture class
Instantiate the Mat class using any of the functions mentioned in this tutorial earper.
// Instantiating the VideoCapture class (camera:: 0) VideoCapture capture = new VideoCapture(0);
Step 3: Read the frames
You can read the frames from the camera using the read() method of the VideoCapture class. This method accepts an object of the class Mat to store the frame read.
// Reading the next video frame from the camera Mat matrix = new Mat(); capture.read(matrix);
Example
The following program demonstrates how to capture a frame using camera and display it using JavaFX window. It also saves the captured frame.
import java.awt.image.BufferedImage; import java.awt.image.DataBufferByte; import java.awt.image.WritableRaster; import java.io.FileNotFoundException; import java.io.IOException; import javafx.apppcation.Apppcation; 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.Core; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.videoio.VideoCapture; pubpc class CameraSnapshotJavaFX extends Apppcation { Mat matrix = null; @Override pubpc void start(Stage stage) throws FileNotFoundException, IOException { // 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(); } pubpc WritableImage capureSnapShot() { WritableImage WritableImage = null; // Loading the OpenCV core pbrary System.loadLibrary( Core.NATIVE_LIBRARY_NAME ); // 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; } pubpc void saveImage() { // Saving the Image String file = "E:/OpenCV/chap22/sanpshot.jpg"; // Instantiating the imgcodecs class Imgcodecs imageCodecs = new Imgcodecs(); // Saving it again imageCodecs.imwrite(file, matrix); } pubpc static void main(String args[]) { launch(args); } }
Output
On executing the program, you will get the following output.
![Capture Frame Using Camera](/opencv/images/capture_frame_using_camera.jpg)
If you open the specified path, you can observe the same frame which is saved as a jpg file.
Advertisements