MATLAB: 2D convolution in in Matlab.

digital image processingImage Processing Toolbox

I = imread ("lena.jpg");
%imshow(I);
K = I;
C = conv2(I, K);
imshow(C);

I am expecting something like the following as indicated in this link .

But, my output is blank:

What could be the possible reason?

And, how can I obtain the expected output?

Best Answer

What could be the possible reason? And, how can I obtain the expected output?

imshow expects that that intensity of a double image is in the range [0-1]. By default, anything less than 0 is displayed as black, and anything more than 1 is displayed as 1.

You can override that behaviour by passing a different range as the 2nd input to imshow or letting imshow use the intensity range of your image by passing []. So:

imshow(C, [])

should fix your problem.

Related Solutions

MATLAB: I cant use the same for loop to interpolate the colomn? Only in row.

You are making a mistake in indexing and length of for loops. Compare it with the following code to see the mistake. Also, there was a typo in two occurrences of Enlarged_le

Lena_half = imread('lena_half.tif');
Row = 512;   % interp1 along row
[m,n,p] = size(Lena_half);
Enlarge_lena = zeros(m, Row, p);
xi = linspace(1, m, Row);
for i = 1:m   % <---- You want to iterate on all rows, not columns
  for j = 1:p
      Enlarged = interp1(1:n,double(Lena_half(i,:,j)),xi);
      Enlarge_lena(i,:,j) = Enlarged;
  end
end
Enlarge_lena = uint8(Enlarge_lena);
figure(1)
imshow(Enlarge_lena)
Col = 512;
[a,b,c] = size(Enlarge_lena);
Enlarge_lenaCol = zeros(Col, b, c);
yi = linspace(1, a, Col);
for d = 1:b  % <--- Iterate on all columns, not rows.
  for o = 1:c
      Enlarged_le = interp1(1:a,double(Enlarge_lena(:,d,o)),yi);  % <-- indexing issue

      Enlarge_lenaCol(:,d,o) = Enlarged_le;  % <-- indexing issue
  end
end
Enlarge_lenaCol = uint8(Enlarge_lenaCol);
figure(2)
imshow(Enlarge_lenaCol)

MATLAB: What is the wrong in this code

S is complex and imfilter() doesn't work on complex images. You might have to work on the real and imaginary images one at a time.

Best Answer

Related Solutions

MATLAB: I cant use the same for loop to interpolate the colomn? Only in row.

MATLAB: What is the wrong in this code

Related Question