Composite Laplacian mask

% Composite Laplacian mask
clear all; close all; clc;
a=imread('moon.tif');
a=im2double(a);
figure,imshow(a),title('Original Image');
[m n]=size(a);
w=[0 -1 0; -1 5 -1;0 -1 0];
b = imfilter(a,w);
figure,imshow(b),title('4-Connected Laplacian-filtered Image');
w1=[-1 -1 -1; -1 9 -1;-1 -1 -1];
b1 = imfilter(a,w1);
figure,imshow(b1),title('8-ConnectedLaplacian-filtered Image');