OpenCV添加文本

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小牛编辑

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2023-03-14

可以使用imgproc类的方法arrowedLine()将文本添加到图像。以下是此方法的语法。

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

该方法接受以下参数 -

mat - 表示要在其上绘制矩形的图像的Mat对象。
text - 表示要添加的文本的字符串变量。
org - 表示图像中左下角文本字符串的Point对象。
fontFace - 表示字体类型的整型变量。
fontScale - 类型为double的变量表示与字体特定的基本大小相乘的缩放因子。
color - 表示矩形颜色的标量对象(BGR)。
thickness - 表示矩形厚度的整数; 默认情况下，厚度值为1。

示例

以下程序演示如何将文本添加到图像并使用JavaFX窗口显示它。

package yiibai.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添加文本到图像示例");

      // 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);
   }
}

执行上面示例代码，得到以下结果 -