plotting_error_detected.m

clc
clear
close all
img = imread('lena.tif');
img_double = im2double(img);
img_uint8 = uint8(img_double * 255);
img_vector = reshape(img_uint8, 1, []);
img_bits = dec2bin(img_vector, 8);
img_bitstream = reshape(img_bits.', 1, []);
input = str2num(img_bitstream')';
M = length(input);
parity_added = zeros(1,13);
error_detected = zeros(1,13);
a = 1;
for m = 14:-1:2
   n = 2^m-1;
   k = 2^m - 1 - m;
   z = floor(M/k);
   L = z*k;
   H = hammgen(m);
   trt = syndtable(H);
   code = encode(input(1:L),n,k,'hamming/binary');
   output1 = bsc(code, 0.9);
   num_parity_bits = m*z
   parity_added(a) = num_parity_bits;
   error_count = 0;
   N = length(output1);
   for i = 1:n:N
     recd = output1(i:min(i+n-1, N));
     syndrome = rem(recd * H',2);
     s = bit2int(syndrome',m);
     if s~=0
       error_count = error_count + 1;
     end
   end
   error_count
   error_detected(a) = error_count;
   a = a + 1;
 end

plot(parity_added(1:5), error_detected(1:5), '-or');
xlabel('Parity bits used');
ylabel('Error detected');