- OpenCV - GUI
- OpenCV - Writing an Image
- OpenCV - Reading Images
- OpenCV - Storing Images
- OpenCV - Environment
- OpenCV - Overview
- OpenCV - Home
Types of Images
Image Conversion
Drawing Functions
- OpenCV - Adding Text
- OpenCV - Drawing Arrowed Lines
- OpenCV - Drawing Convex Polylines
- OpenCV - Drawing Polylines
- OpenCV - Drawing an Ellipse
- OpenCV - Drawing a Rectangle
- OpenCV - Drawing a Line
- OpenCV - Drawing a Circle
Blur
Filtering
- OpenCV - Image Pyramids
- OpenCV - Morphological Operations
- OpenCV - Erosion
- OpenCV - Dilation
- OpenCV - Filter2D
- OpenCV - SQRBox Filter
- OpenCV - Box Filter
- OpenCV - Bilateral Filter
Thresholding
Sobel Derivatives
Transformation Operations
Camera and Face Detection
Geometric Transformations
Miscellaneous Chapters
OpenCV Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
OpenCV - Filter2D
The Filter2D operation convolves an image with the kernel. You can perform this operation on an image using the Filter2D() method of the imgproc class. Following is the syntax of this method −
filter2D(src, dst, ddepth, kernel)
This method accepts the following parameters −
src − A Mat object representing the source (input image) for this operation.
dst − A Mat object representing the destination (output image) for this operation.
ddepth − A variable of the type integer representing the depth of the output image.
kernel − A Mat object representing the convolution kernel.
Example
The following program demonstrates how to perform the Filter2D operation on an image.
import org.opencv.core.Core; import org.opencv.core.CvType; import org.opencv.core.Mat; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; pubpc class Filter2D { pubpc static void main( String[] args ) { //Loading the OpenCV core pbrary System.loadLibrary( Core.NATIVE_LIBRARY_NAME ); //Reading the Image from the file and storing it in to a Matrix object String file ="E:/OpenCV/chap11/filter_input.jpg"; Mat src = Imgcodecs.imread(file); //Creating an empty matrix to store the result Mat dst = new Mat(); // Creating kernel matrix Mat kernel = Mat.ones(2,2, CvType.CV_32F); for(int i = 0; i<kernel.rows(); i++) { for(int j = 0; j<kernel.cols(); j++) { double[] m = kernel.get(i, j); for(int k = 1; k<m.length; k++) { m[k] = m[k]/(2 * 2); } kernel.put(i,j, m); } } Imgproc.filter2D(src, dst, -1, kernel); Imgcodecs.imwrite("E:/OpenCV/chap11/filter2d.jpg", dst); System.out.println("Image Processed"); } }
Assume that following is the input image filter_input.jpg specified in the above program.
![Filter Input](/opencv/images/filter_input.jpg)
Output
On executing the program, you will get the following output −
Image Processed
If you open the specified path, you can observe the output image as follows −
![Filter2D](/opencv/images/filter2d.jpg)