OpenCV新增文字

可以使用imgproc類的方法arrowedLine()將文字新增到影象。 以下是此方法的語法。

putText(img, text, org, fontFace, fontScale, Scalar color, int thickness)

該方法接受以下引數 -

• mat - 表示要在其上繪製矩形的影象的Mat物件。
• text - 表示要新增的文字的字串變數。
• org - 表示影象中左下角文字字串的Point物件。
• fontFace - 表示字型型別的整型變數。
• fontScale - 型別為double的變數表示與字型特定的基本大小相乘的縮放因子。
• color - 表示矩形顏色的標量物件(BGR)。
• thickness - 表示矩形厚度的整數; 預設情況下，厚度值為1。

範例

以下程式演示如何將文字新增到影象並使用JavaFX視窗顯示它。

package tw511.com;

import java.awt.image.BufferedImage;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import javax.imageio.ImageIO;

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.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

public class AddingTextToImage extends Application {
   Mat matrix = null;

   @Override
   public void start(Stage stage) throws Exception {
      // Capturing the snapshot from the camera
      AddingTextToImage obj = new AddingTextToImage();
      WritableImage writableImage = obj.LoadImage();

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

      // setting the fit height and width of the image view
      imageView.setFitHeight(600);
      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("OpenCV新增文字到影象範例");

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

      // Displaying the contents of the stage
      stage.show();
   }
   public WritableImage LoadImage() throws Exception {
      // Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );

      // Reading the Image from the file and storing it in to a Matrix object
      String file ="F:/worksp/opencv/images/sample2.jpg";
      Mat matrix = Imgcodecs.imread(file);
      String addText = "This is a Text String ~";
      // Adding Text
      Imgproc.putText (
         matrix,                          // Matrix obj of the image
         addText,                         // Text to be added
         new Point(100, 150),               // point
         Core.FONT_HERSHEY_SIMPLEX ,      // front face
         1,                               // front scale
         new Scalar(0, 0, 0),             // Scalar object for color
         2                                // Thickness
      );

      // Encoding the image
      MatOfByte matOfByte = new MatOfByte();
      Imgcodecs.imencode(".jpg", matrix, matOfByte);

      // Storing the encoded Mat in a byte array
      byte[] byteArray = matOfByte.toArray();

      // Displaying the image
      InputStream in = new ByteArrayInputStream(byteArray);
      BufferedImage bufImage = ImageIO.read(in);
      this.matrix = matrix;

      //Creating the Writable Image
      WritableImage writableImage = SwingFXUtils.toFXImage(bufImage, null);
      return writableImage;
   }
   public static void main(String args[]) {
      launch(args);
   }
}

執行上面範例程式碼，得到以下結果 -