title: MATLAB Image Sharpening - Gaussian High Pass Filter using (1- Gaussian Low Pass Filter)
body: <p>I am trying to sharpen an image by designing a Gaussian High-Pass Filter. I would like to do this using the fact that the high-pass filter is equivalent to the identity matrix minus the low-pass filter, so I did the following:</p>
  
  <pre><code>image= imread('Question3_Data-Cats.jpg'); % read image
  
  H = 1 - fspecial('gaussian' ,[5 5],2); % create unsharp mask
  sharpened = imfilter(image,H);  % create a sharpened version of the image using that mask
  
  imshow([image sharpened]); %showing input &amp; output images
  </code></pre>
  
  <p>I did not get a sharpened image. Instead, I got a white image with some colors on a small region of the image. Can someone help? Thank you.</p>