how to find high pass filtered version of a image with 3 by 3-pixel standard approximation of the Laplacian operator?

I want to find out the edge preservation index (beta)of medical images.Are the following MATLAB codes give me the high pass filtered version of a gray -scale image, obtained with a 3 by 3-pixel standard approximation of the Laplacian operator? please help me as soon as possible..

clc; 
clear all;
close all;
img=imread('my image.jpg');
H = fspecial('laplacian');
k = imfilter(img,H);