Comparing individual matrix elements in MATLAB?

Question

I need to compare a value in a multidimentional array and according to this comparison, I need to assign a value of another matrix in the same index to a new matrix of the same size in the same index. Can you give me an idea on how to do this?

Here's the code below using the for loop, but I need to do this without using a for loop.

for i = 1:sizeOfMatrix(1, 1)
   for j = 1:sizeOfMatrix(1, 2)
      if grayImage(i, j) > t
          result(i, j) = 0;
      else
          result(i, j) = grayImage(i, j);
      end
   end
end

where t is the value that I need to compare with.

Answer 1

Use logical indexing:

result = zeros(size(grayImage));
result(grayImage <= t) = grayImage(grayImage <= t);

This is a much faster and cleaner way to access matrix elements conditionally.

Alternatively, you can do:

result = grayImage;
result(grayImage > t) = 0;