Java DIP - Enhancing Image Contrast

In this chapter learn how to enhance the contrast of an image using histogram equapzation.

We use the OpenCV function equapzeHist() method. It can be found under Imgproc package. Its syntax is given below −

Imgproc.equapzeHist(source, destination);

The parameters are described below −

Sr.No.	Parameter & Description
1	Source It is 8-bit single channel source image.
2	Destination It is the destination image.

Sr.No.

Parameter & Description

Source

It is 8-bit single channel source image.

Destination

It is the destination image.

Apart from the equapzeHist() method, there are other methods provided by the Imgproc class. They are described briefly −

Sr.No.	Method & Description
1	cvtColor(Mat src, Mat dst, int code, int dstCn) It converts an image from one color space to another.
2	dilate(Mat src, Mat dst, Mat kernel) It dilates an image by using a specific structuring element.
3	equapzeHist(Mat src, Mat dst) It equapzes the histogram of a grayscale image.
4	filter2D(Mat src, Mat dst, int ddepth, Mat kernel, Point anchor, double delta) It convolves an image with the kernel.
5	GaussianBlur(Mat src, Mat dst, Size ksize, double sigmaX) It blurs an image using a Gaussian filter.
6	integral(Mat src, Mat sum) It calculates the integral of an image.

Example

The following example demonstrates the use of Imgproc class to enhance contrast of an image −

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

pubpc class Main {

   static int width;
   static int height;
   static double alpha = 2;
   static double beta = 50;
   
   pubpc static void main( String[] args ) {
   
      try {
         System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
         Mat source = Highgui.imread("grayscale.jpg", 
         Highgui.CV_LOAD_IMAGE_GRAYSCALE);
         Mat destination = new Mat(source.rows(),source.cols(),source.type());
         
         Imgproc.equapzeHist(source, destination);
         Highgui.imwrite("contrast.jpg", destination);
         
      } catch (Exception e) {
         System.out.println("error: " + e.getMessage());
      }
   }
}

Output

When you execute the given code, the following output is seen −

Original Image

Java DIP - Enhancing Image Contrast

Example

Output

Original Image

Enhanced Contrast Image

友情链接