Manipulate '1' values in binary matrix

I have a binary matrix and I need to create a convolving function that manipulates only the '1' values. In other words, I want to create second matrix where the '0' values remain in the same place but the '1' values are replaced with the output of the function that manipulated them. Any thoughts?

Answer 1

[Image Analyst]

Just create a mask for the zeros and multiply your output by the mask

% Create mask
mask = originalMatrix == 0;
% Do the convolving with conv2d() or any custom function you want
% to get some new matrix.
newMatrix = conv2d(originalMatrix, yourKernel, 'same');
% Put zeros of original back in
newMatrix(mask) = 0;

[Ana]

Thank you Image Analyst! Both answers were very helpful.