Smoothing an image

Smoothing an image, also called blurring, will make the edges of an image smoother. Blurring is the process of making an image less distinct. We recognize blurred objects when we take a picture with the camera out of focus. Blurring can be used for special effects. Here, we will use it to create an image that we will then sharpen.

The following example loads an image of a cat and repeatedly applies the blur method to the image. In this example, the process is repeated 25 times. Increasing the number of iterations will result in more blur or smoothing.

The third argument of the blur method is the blurring kernel size. The kernel is a matrix of pixels, 3 by 3 in this example, that is used for convolution. This is the process of multiplying each element of an image by weighted values of its neighbors. This allows neighboring values to effect an element's value:

Mat source = Imgcodecs.imread("cat.jpg"); 
Mat destination = source.clone(); 
for (int i = 0; i < 25; i++) { 
    Mat sourceImage = destination.clone(); 
    Imgproc.blur(sourceImage, destination, new Size(3.0, 3.0)); 
} 
Imgcodecs.imwrite("smoothCat.jpg", destination); 

The following is the original image:

The enhanced image follows: