EPI.m

% Script to compute Edge preservation index

% Edge preservation index created on 28-11-2017, R.Sudhakar
% equation through paper from Farook Sataar, IEEE transactions on IP vol 6 no 6 June 1997

[fname, pthname]=uigetfile('*.jpg;*.png;*.tif;*.bmp','Select the Filtered Image'); %select image
% get the original image of your choice
s=imread([pthname fname]);
% add with the type of noise along with density
[fname, pthname]=uigetfile('*.jpg;*.png;*.tif;*.bmp','Select the Noisy Image'); %select image
ns=imread([pthname fname]);
% a high pass laplacian filter is created
H = fspecial('laplacian',0.5) ;
% noisy image is restored  with median filter of size 3 X 3
y=medfilt2(ns);
% preparing the components of EPI
% input image is highpass filtered with laplacian filter
deltas=imfilter(s,H);
meandeltas=mean2(deltas);
% Restored Image is highpass filtered with laplacian filter
deltascap=imfilter(y,H);
meandeltascap=mean2(deltascap);
% computation of EPI
p1=deltas-meandeltas;
p2=deltascap-meandeltascap;
num=sum(sum(p1.*p2));
den=(sum(sum(p1.^2)))*(sum(sum(p2.^2)));
epi=num/sqrt(den)
% figure(1);
% imshow(s)
% figure(2);
% imshow(ns);
% figure(3);
% imshow(y);
% figure(4);
% imshow(deltas);
% figure(5);
% imshow(deltascap);