OpenCV彩色圖像轉爲二進制

使用threshold()方法將灰度圖像轉換爲二進制值圖像。以下是此方法的語法。

threshold(Mat src, Mat dst, double thresh, double maxval, int type)

該方法接受以下參數 -

• mat - 表示輸入圖像的Mat對象。
• dst - 表示輸出圖像的Mat對象。
• thresh - 表示閾值的整數。
• maxval - 一個整數，表示與THRESH_BINARY和THRESH_BINARY_INV閾值類型一起使用的最大值。
• type - 表示轉換類型的整數代碼，例如RGB到灰度。

通過將代碼Imgproc.THRESH_BINARY與值一起傳遞給其餘參數，可以將灰度圖像轉換爲二值圖像。

示例

以下程序演示如何將彩色圖像作爲二進制圖像讀取並使用JavaFX窗口顯示。

package yiibai.com;

import java.awt.image.BufferedImage;

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

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;

public class ColorToBinary extends Application {
   @Override
   public void start(Stage stage) throws Exception {
      WritableImage writableImage = loadAndConvert();

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

      // Setting the position of the image
      imageView.setX(10);
      imageView.setY(10);

      // 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("Loading an image");

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

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

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

      // File input = new File("C:/EXAMPLES/OpenCV/sample.jpg");
      String input = "F:/worksp/opencv/images/sample.jpg";

      // Reading the image
      Mat src = imageCodecs.imread(input);

      // Creating the destination matrix
      Mat dst = new Mat();

      // Converting to binary image...
      Imgproc.threshold(src, dst, 200, 500, Imgproc.THRESH_BINARY);

      // Extracting data from the transformed image (dst)
      byte[] data1 = new byte[dst.rows() * dst.cols() * (int)(dst.elemSize())];
      dst.get(0, 0, data1);

      // Creating Buffered image using the data
      BufferedImage bufImage = new BufferedImage(dst.cols(),dst.rows(), 
         BufferedImage.TYPE_BYTE_GRAY);

      // Setting the data elements to the image
      bufImage.getRaster().setDataElements(0, 0, dst.cols(), dst.rows(), data1);

      // Creating a Writable image
      WritableImage writableImage = SwingFXUtils.toFXImage(bufImage, null);

      System.out.println("Converted to binary");
      return writableImage;
   }  
   public static void main(String args[]) throws Exception {
      launch(args);
   }
}

輸入圖像，假定以下是上述程序中指定的輸入圖像sample.jpg。

在執行程序時，您將得到以下輸出。