Re: [WM]: Watermarking using Modified Trellis

["Frank Ling" <lhefei@163.com>]

Hello, madan mohan

    	I have implemented this method, but i found the idea that each arch is generated randomly is not good. An elaborate trellis
structure is better.  the fowllowing code maybe help you.

function [isok,trellis] = createTrellis(key,InputK, InputM, OutputN)

% key = 1234;
%
% InputK = 2;
% OutputN=12;
% InputM=2;

numInputSymbols = 2^InputK;
numStates = 2^InputM;
numOutputSymbols =  2^OutputN;

% seed = randseed(key);
Keys = randseed(key,numStates);
Keys = Keys';
% Keys = randint(numStates,1,[0,2147483647]);


for i = 1:numStates
   NextStateEven(i,:) = mod((i-1),2):2:(numInputSymbols-1);  %represent 0
   NextStateOdd(i,:) = mod(i,2):2:(numInputSymbols-1);   %represent 1   
   NextState(i,1:2:numInputSymbols) =  NextStateEven(i,:);
   NextState(i,2:2:numInputSymbols) =  NextStateOdd(i,:); end

% compute how many outlets for each state

numOutputPerS = numInputSymbols;

CycleNum = (InputM + InputK)/(OutputN - InputM - InputK);

for i = 1:numStates
    rand('state',Keys(i));
    tmp = randint(numOutputPerS,OutputN);
    
    TempDec(1:numOutputPerS) = 0;
    nn = size(tmp,2);
    for kk = 1:nn
        TempDec(:) = TempDec(:)*2 + tmp(:,kk);
    end
    
    
    TmpOct = base2dec(dec2base(TempDec,8),10);
    
   NextOutput(i,:) = TmpOct';
end

trellis = struct('numInputSymbols',numInputSymbols,'numOutputSymbols',numOutputSymbols,...
'numStates',numStates,'nextStates',NextState,...
'outputs',NextOutput);

[isok,status] = istrellis(trellis);


Frank Ling



======= 2005-01-19 14:31:55 =======

>Hi,
> 
>I'm doing my project based on IEEE paper "Applying informed coding and 
>embedding to design a robust high capacity watermark by M.L.Miller, Gwenael J.Doerr and I.J.Cox.
>I have doubt in making a modified trellis structure for encoding process described in the paper. I would like  to implement it
>matlab. Can any one help me in the process of implementing in matlab?    
> 
>thank you in advance,
> 
>Madan


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