這個隱寫術提取代碼有什麼問題？

Question

我想嘗試從已插入的消息before..but有與說明書波紋管的錯誤圖像中提取消息..

此代碼提取物：

% Read Image Stego 
IS = imread('imagestego.bmp'); 

% Extract RedChannel 
RedChannel = IS(:,:,1); 

% Convert RedChannel to biner 
bitstego = uint8(reshape(dec2bin(RedChannel,8)',1,[]) = '0'); 
nBitstego = length(bitstego); 

% Extraction 
extBits = bitget(RedChannel(1:end),1).'; 
extMessage = char(bin2dec(reshape(int2str(extBits),8,[]).').'); 

，並從提取的代碼此錯誤：

>> latihanextract 
Error: File: latihanextract.m Line: 8 Column: 55 
The expression to the left of the equals sign is not a valid target for an assignment. 

這是嵌入代碼之前..它的工作！

coverImage = imread('foto1.jpg'); 
message = 'IMRON'; 

%EMBEDDING 
RedChannel = coverImage(:,:,1); 
GreenChannel = coverImage(:,:,2); 
BlueChannel = coverImage(:,:,3); 
bits = uint8(reshape(dec2bin(message,8)',1,[]) - '0'); 
nBits = length(bits); 
RedChannel(1:nBits) = bitset(RedChannel(1:nBits),1,bits); 
Imageresults = cat(3,RedChannel,GreenChannel,BlueChannel); 
imwrite(Imageresults,'imagestego.bmp'); 

所以有什麼問題？

Answer 1

這是你的問題......

% Read Image Stego 
IS = imread('stegosaurus.bmp'); 

% Extract RedChannel 
RedChannel = IS(:,:,1); 

% Convert RedChannel to binary 
bitstego = uint8(reshape(dec2bin(RedChannel,8)',1,[]) - '0'); 
nBitstego = length(bitstego); 
% the previous 2 lines are actually unnecessary and can be deleted... 
% see explanation in text below 

% Extrication 
extBits = bitget(RedChannel(1:end),1).'; % (1:end) gives you all of the elements 
extMessage = char(bin2dec(reshape(int2str(extBits),8,[]).').') 

你經位的圖像的數量，而不是字節數試圖循環。 bitstego是bitstego中所有字節的二進制表示形式，因此bitstego的長度是RedChannel的8倍。

在這種情況下，使用特殊索引end來獲取RedChannel中的元素數量要容易得多。