如何在图像中封装一些文本信息并使用MATLAB解压缩？

问题描述

  new_img = convert（img，text）; 
（img，text）= convert_back（new_img）;有人可以用MATALB的内置图像说明吗？
 
 
 
  

解决方案

我相信你正在寻找。您可以从的MATLAB实施开始。

进行LSB隐写术的一种简单方法是采用无损压缩图像并设置每个分量（R，G，B）的LSB。然后，对于 m x n 图像，您将获得3mn 位来存储信息。由于您修改LSB，因此不会

更新

所以我决定编写一个小，低效但示范的例子：

 函数LSBStega 
 %% //图像和文本
 I = imread（ 'coins.png'）; 
 text ='Hello World etc'; 
 assert（numel（I）> numel（text）* 8，'像素数不足'）; 
 
 %% //编码
％//结束字符表示隐藏文本的结尾
 end_char ='。'; 
％//追加
 text = [text end_char]; 
％//将每个字符转换为具有至少8位的二进制形式
％//因为二进制表示
％//将每个字符存储在二进制中行和（:)操作
％//通过列向量化矩阵。 
 b =转置（dec2bin（text，8））; 
％//查找哪些位应设置为1或0 
 ind_0 = find（b =='0'）; 
 ind_1 = find（b =='1'）; 
％//将适当的位设置为1和0，并单独休息
 I（ind_0）= bitset（I（ind_0），1,0）; 
 I（ind_1）= bitset（I（ind_1），1,1）; 
 
 %% //更快的解码
 text_back = []; 
 for i = 1：8：numel（I）
％//从图像中的一组8个字节中提取LSB 
 C = bitget（I（i：i + 7） ，1）; 
％//从二进制转换为十进制
 C = bin2dec（num2str（C））; 
％//检查是否是结束字符;如果没有，则存储
如果（C == end_char）
 break; 
 else 
 text_back（end + 1）= C; 
 end 
 end 
％//转换为文本
 text_back = char（text_back）; 
 
 %% //显示
子图（1,2,1）; 
 title（'Original'）; 
 imshow（imread（'coins.png'））; 
子图（1,2,2）; 
标题（'Steganography Result'）; 
 imshow（I）; 
 disp（text_back）; 
 end 
  

new_img = convert(img, text);
(img, text) = convert_back(new_img);

Can someone illustrate with a built-in image of MATALB?

解决方案

I believe you're looking for steganography. You can start with this MATLAB implementation of LSB steganography.

A simple way of doing LSB steganography is to take an lossless-compressed image and set the LSB of each component (R,G,B). Then for a m x n image you get 3mn bits to store information in. Since you're modifying the LSB, the difference will not be perceivable in the image.

Update

SO I decided to code up a small, inefficient but demonstrative example:

function LSBStega
        %%// Image and text
        I = imread('coins.png');
        text = 'Hello World etc';
        assert(numel(I) > numel(text)*8,'Insufficient number of pixels');

        %%// Encode
        %// The end character signifies the end of the hidden text
        end_char = '.';
        %// Append it
        text = [text end_char];
        %// Convert each character into binary form with atleast 8 bits
        %// We transpose it before calling (:) since the binary representation
        %// is stores each character in binary per row and the (:) operations
        %// vectorizes the matrix by column.
        b = transpose(dec2bin(text,8));
        %// Find which bits should be set to 1 or 0
        ind_0 = find(b == '0');
        ind_1 = find(b == '1');
        %// Set the appropriate bits to 1 and 0 and leave the rest alone
        I(ind_0) = bitset(I(ind_0),1,0);
        I(ind_1) = bitset(I(ind_1),1,1);

        %%// Faster decode
        text_back = [];
        for i = 1:8:numel(I)
            %// Extract the LSB from a set of 8 bytes in the image
            C = bitget(I(i:i+7),1);
            %// Convert from binary to decimal
            C = bin2dec(num2str(C));
            %// Check if it's the end character; break if so, store if not
            if(C == end_char)
                break;
            else
                text_back(end+1) = C;
            end
        end
        %// Convert to text
        text_back = char(text_back);

        %%// Display
        subplot(1,2,1);
        title('Original');
        imshow(imread('coins.png'));
        subplot(1,2,2);
        title('Steganography Result');
        imshow(I);
        disp(text_back);
end

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