how image sharpening is perform in matlab?

please suggest.

% Filter 1
kernel3 = [-1 -1 -1; -1 8 -1; -1 -1 -1]/3;
% Filter the image.  Need to cast to single so it can be floating point
% which allows the image to have negative values.
filteredImage = imfilter(single(im), kernel3);
filteredImage =im2double(filteredImage);
filteredImage =1.5 .*filteredImage;
figure(),imshow(filteredImage);
out1=imadd(im,filteredImage);
figure(), imshow(out1);
Z = imabsdiff(im,out1);
% figure(), 
imtool(Z);

Answer 1

[Jaimin]

Hi @Durgesh Naik

There are three methods to perform image sharpening which are as follows:

Using a Sharpening Kernel : This method enhances edges by using a high-pass filter. Refer to the following code snippet to learn more about implementing high-pass filter.

% Read the image
im = imread('example.jpg');

% Convert the image to grayscale if it's not already
if size(im, 3) == 3
    im = rgb2gray(im);
end

% Define a Laplacian kernel for sharpening
sharpeningKernel = [-1 -1 -1; -1 8 -1; -1 -1 -1];

% Apply the filter using imfilter
sharpenedImage = imfilter(double(im), sharpeningKernel, 'replicate');

% Display the original and sharpened images
figure;
subplot(1, 2, 1), imshow(im), title('Original Image');
subplot(1, 2, 2), imshow(uint8(sharpenedImage)), title('Sharpened Image');

Using Unsharp Masking: Unsharp masking is a popular technique that enhances edges by subtracting a blurred version of the image from the original.

Refer to the following code snippet to learn more about unsharp masking.

% Read the image
im = imread('example.jpg');

% Convert the image to grayscale if it's not already
if size(im, 3) == 3
    im = rgb2gray(im);
end

% Perform Gaussian blur
blurredImage = imgaussfilt(im, 2);

% Calculate the mask
mask = double(im) - double(blurredImage);

% Add the mask to the original image to get the sharpened image
sharpenedImage = double(im) + 1.5 * mask;

% Display the original and sharpened images
figure;
subplot(1, 2, 1), imshow(im), title('Original Image');
subplot(1, 2, 2), imshow(uint8(sharpenedImage)), title('Sharpened Image');

Using Built-in MATLAB Function : MATLAB provides a built-in function “imsharpen” for image sharpening.

Refer to the following code snippet to learn more about “imsharpen” function.

% Read the image
im = imread('example.jpg');

% Sharpen the image using imsharpen
sharpenedImage = imsharpen(im);

% Display the original and sharpened images
figure;
subplot(1, 2, 1), imshow(im), title('Original Image');
subplot(1, 2, 2), imshow(sharpenedImage), title('Sharpened Image');

For more information regarding “imsharpen” please follow this MathWorks Documentation.

https://www.mathworks.com/help/images/ref/imsharpen.html

I hope it helps.