Java DIP-应用水印 - 芒果文档

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📜 Java DIP-应用水印

📅 最后修改于: 2020-12-14 05:40:53 🧑 作者: Mango

在本章中，我们学习在图像上应用水印的两种方法。这些方式是-

应用文字水印
应用图像水印

应用文字水印

我们使用OpenCV函数putText将文本水印应用于图像。可以在Core软件包下找到。其语法如下-

Core.putText(source, Text, Point, fontFace ,fontScale , color);

该函数的参数如下所述-

Sr.No.	Parameter & Description
1	Source It is source image.
2	Text It is the string text that would appear on the image.
3	Point It is the point where text should appear on image.
4	fontFace Font type. For example − FONT_HERSHEY_SIMPLEX, FONT_HERSHEY_PLAIN, FONT_HERSHEY_COMPLEX etc.
5	fontScale It is font scale factor that is multiplied by the font-specific base size.
6	color It is text color.

除了putText方法外，Core类还提供了其他方法。他们简要描述-

Sr.No.	Method & Description
1	normalize(Mat src, Mat dst, double alpha, double beta, int norm_type) It normalizes the norm or value range of an array.
2	perspectiveTransform(Mat src, Mat dst, Mat m) It performs the perspective matrix transformation of vectors.
3	phase(Mat x, Mat y, Mat angle) It calculates the rotation angle of 2D vectors.
4	rectangle(Mat img, Point pt1, Point pt2, Scalar color) It draws a simple, thick, or filled up-right rectangle.
5	reduce(Mat src, Mat dst, int dim, int rtype, int dtype) It reduces a matrix to a vector.
6	transform(Mat src, Mat dst, Mat m) It performs the matrix transformation of every array element.

例

以下示例演示了如何使用Core类将文本水印应用于图像-

import org.opencv.core.Core;
import org.opencv.core.Mat;

import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

public class Main {
   public static void main( String[] args ) {
   
      try{
         System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
         Mat source = Highgui.imread("digital_image_processing.jpg",  Highgui.CV_LOAD_IMAGE_COLOR);
         Mat destination = new Mat(source.rows(),source.cols(), source.type());  
         
         Core.putText(source, "Tutorialspoint.com", new Point  (source.rows()/2,source.cols()/2), Core.FONT_ITALIC,new Double(1),new  Scalar(255));

         Highgui.imwrite("watermarked.jpg", source);
         
      } catch (Exception e) {
         System.out.println("Error: "+e.getMessage());
      }
   }
}

输出

当您执行给定的代码时，将看到以下输出-

原始图片

应用WaterMark教程

文字水印图像

应用WaterMark教程

在图像上应用图像水印

我们将使用OpenCV函数addWeighted将图像水印应用于图像。可以在Core软件包下找到。其语法如下-

Core.addWeighted(InputArray src1, alpha, src2 (Watermark image), beta, gamma, OutputArray dst);

该函数的参数如下所述-

Sr.No.	Parameter & Description
1	src1 It is first input array.
2	alpha It is the weight of the first array elements.
3	src2 It is the second input array of the same size and channel number as src1.
4	beta It is the weight of the second array elements.
5	gamma It is the scalar added to each sum.
6	dst It is the output array that has the same size and number of channels as the input arrays.

例

以下示例演示了如何使用Core类将图像水印应用于图像-

import org.opencv.core.Core;
import org.opencv.core.Mat;

import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

public class Main {
   public static void main( String[] args ) {
   
      try{
         System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
         
         Mat source = Highgui.imread("digital_image_processing.jpg",  Highgui.CV_LOAD_IMAGE_COLOR);
         Mat waterMark = Highgui.imread("watermark.png",  Highgui.CV_LOAD_IMAGE_COLOR);
         Rect ROI = new Rect(waterMark.rows() * 4,waterMark.cols(),  waterMark.cols(),waterMark.rows());
         
         Core.addWeighted(source.submat(ROI), 0.8, waterMark, 0.2, 1,  source.submat(ROI));
         Highgui.imwrite("watermarkedImage.jpg", source);
         
      } catch (Exception e) {
         System.out.println("Error: " + e.getMessage());
      }
   }
}

输出

当您执行给定的代码时，将看到以下输出-

原始图片

应用WaterMark教程

水印图像

应用WaterMark教程

带水印的图像

应用WaterMark教程