Index exceeds the number of array elements (2). Error in Hindawi_Extract (line 20) msg=strcat​(msg,num2s​tr(m1(loop​)));

I=imread('C:\Users\manav\Desktop\MinoR Project\Code\Digital-Image_Steganography-Using-8Directional-PVD-master\teapot.png');

var123=[];

final_msg=[];

i1=1;

checker='000000000000000000000000000000';

msg='';

while(i1<=510)

for j1=1:3:510

pixel_count=0;

for i=i1:i1+2

for j=j1:j1+2

pixel_count=pixel_count+1;

if(pixel_count==5)

A1=i;

A2=j;

m1=dec2bin(I(i,j),2);

for loop=3:-1:1

msg=strcat(msg,num2str(m1(loop)));

var123=strfind(msg,checker);

if(length(var123)>=1)

break

end

end

if(length(var123)>=1)

break

end

end

end

if(length(var123)>=1)

break

end

end

inner_loop=0;

for x1=i1:i1+2

for x2=j1:j1+2

inner_loop=inner_loop+1;

if(inner_loop~=5)

if(I(x1,x2)>I(A1,A2))

di=I(x1,x2)-I(A1,A2);

elseif(I(x1,x2)==I(A1,A2))

di=0;

else

di=I(A1,A2)-I(x1,x2);

end

if(di<8)

L=0;

ti=3;

elseif(di>7 && di<16)

L=8;

ti=3;

elseif(di>15 && di<32)

L=16;

ti=3;

elseif(di>31 && di<64)

L=32;

ti=3;

elseif(di>63 && di<128)

L=64;

ti=4;

else

L=128;

ti=4;

end

S=di-L;

binary_form=fliplr(dec2bin(S,ti));

for k=1:ti

msg=strcat(msg,num2str(binary_form(k)));

var123=strfind(msg,checker);

if(length(var123)>=1)

break

end

end

if(length(var123)>=1)

break

end

end

end

if(length(var123)>=1)

break

end

end

if(length(var123)>=1)

break

end

end

if(length(var123)>=1)

break

end

i1=i1+3;

end

lkj=var123(1);

lkj=lkj+6;

msg;

msg=msg(1:lkj);

msg;

final_msg=[];

ccc=0;

len_msg=floor(length(msg)/8);

for outer_loop=1:len_msg

ccc=ccc+1;

final_msg(outer_loop)=bin2dec(fliplr(msg(ccc:ccc+7)));

ccc=ccc+7;

end

final_msg=char(final_msg);

DISP("extract");

Answer 1

[Cris LaPierre]

Let's break down the error message.

"Index exceeds the number of array elements (2). Error in Hindawi_Extract (line 20) msg=strcat(msg,num2str(m1(loop)));"

The error is in line 20, specifically

 msg=strcat(msg,num2str(m1(loop)));

It is an indexing error, so we only have to inspect variables that are indexed.

 m1(loop)

The index, which is loop, exceeds the number of array elements. Your array is m1, and it only has 2 elements (this is indicated by the (2) in the error message).

This means that either m1 is not the size you think it is, or loop contains a value larger than expected. Those are great places to start looking into your code to determine why it is not doing what you expect.