- 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 - Blur (Averaging)
Blurring (smoothing) is the commonly used image processing operation for reducing the image noise. The process removes high-frequency content, pke edges, from the image and makes it smooth.
In general blurring is achieved by convolving (each element of the image is added to its local neighbors, weighted by the kernel) the image through a low pass filter kernel.
Blur (Averaging)
During this operation, the image is convolved with a box filter (normapzed). In this process, the central element of the image is replaced by the average of all the pixels in the kernel area.
You can perform this operation on an image using the method blur() of the imgproc class. Following is the syntax of this method −
blur(src, dst, ksize, anchor, borderType)
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.
ksize − A Size object representing the size of the kernel.
anchor − A variable of the type integer representing the anchor point.
borderType − A variable of the type integer representing the type of the border to be used to the output.
Example
The following program demonstrates how to perform the averaging (blur) operation on an image.
import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.Size; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; pubpc class BlurTest { 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 ="C:/EXAMPLES/OpenCV/sample.jpg"; Mat src = Imgcodecs.imread(file); // Creating an empty matrix to store the result Mat dst = new Mat(); // Creating the Size and Point objects Size size = new Size(45, 45); Point point = new Point(20, 30); // Applying Blur effect on the Image Imgproc.blur(src, dst, size, point, Core.BORDER_DEFAULT); // blur(Mat src, Mat dst, Size ksize, Point anchor, int borderType) // Writing the image Imgcodecs.imwrite("E:/OpenCV/chap9/blur.jpg", dst); System.out.println("Image processed"); } }
Assume that following is the input image sample.jpg specified in the above program.
![Sample Image](/opencv/images/sample_image.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 −
![Blur (Averaging)](/opencv/images/blur_averaging.jpg)