Matlab laplacian filter doesn't work properly

Hey guys! I am trying to apply a Laplacian filter on a picture but it just doesn't look like what it's supposed to be even if I followed all the steps (I found some questions here, but they still didn't help).

Here is my code and the input and output image and the image I am supposed to have.

my_img= imread ('D:\343a.tif');
[rows, columns, nBands] = size(my_img)
K4 = [ -1,-1,-1; -1,8, -1; -1,-1,-1];  

filteredImage= conv2(double(my_img), K4,"same");
minR = min(filteredImage(:));
maxR = max(filteredImage(:));
filteredImage = (filteredImage - minR) / (maxR - minR);

figure 1
imshow(filteredImage, []);

Answer 1

[Image Analyst]

It's because you're not scaling your positive and negative values equally so the zero level is not at zero. Try this:

grayImage = imread ('D:\Matlab\work\Tests\hhhh.PNG');
[rows, columns, numberOfColorBands] = size(grayImage)
if numberOfColorBands > 1
  grayImage = rgb2gray(grayImage);
end
% Crop image to chop off white stuff and image on the right.
grayImage = grayImage(24:328, 1:160);
% Display the image.
subplot(1, 2, 1);
imshow(grayImage, []);
title('Original Image', 'FontSize', 20);

% Do the convolution.
kernel = [-1,-1,-1; -1,8,-1; -1,-1,-1]; 
filteredImage= conv2(double(grayImage), kernel, 'same');

% minR = min(filteredImage(:))
% maxR = max(filteredImage(:))

% Find the max value, regardless if it's positive or negative.
peakValue = max(abs(filteredImage(:)))

% Display the image with equal range in both the positive and negative direction.
subplot(1, 2, 2);
imshow(filteredImage, [-peakValue, peakValue]);
title('Filtered Image', 'FontSize', 20);