You can achieve the same result as returned imtophat function only using imerode and imdilate.
% Load the image
original = imread('rice.png');
% Define the morphological structuring element (you can change it according to your application)
se = strel('disk', 12);
% Perform top-hat filtering without using imtophat(__)
openedImg = imdilate(imerode(original, se), se);
tophatFiltered1 = original - openedImg;
Now, calculate the same using imtophat
% Load the image
original = imread('rice.png');
% Define the morphological structuring element (you can change it according to your application)
se = strel('disk', 12);
% Perform top-hat filtering using imtophat(__)
tophatFiltered2 = imtophat(original, se);
Check if both approaches are giving the same results
isequal(tophatFiltered1, tophatFiltered2)
ans =
logical
1
