Point Detection on Image

clear all ; close all; clc;
I = imread('House24.png');
I = rgb2gray(I);
I = im2double(I);
h = [-1 -1 -1;-1 8 -1;-1 -1 -1];
f = imfilter(I,h);
figure,imshow(I),title('Original Image');
figure,imshow(f),title('After filtering');