图像隐藏 matlab 代码

%% HIDE THE SIX TEXT PAGES IN A COLOR IMAGE %% About me: % * A.Cherma Rajan,(2003-2007 Batch), % * BE.,Electronics & Communication Engineering, % * Kamaraj college of Engineering and Technology, % * Madurai-1, % * India. % * E-mail:chermarajan@yahoo.co.in % %% About this Program: % This program can encode the text images (6 images max) in a single color image. And also % can easily recover the texts already being hided. It is very simple one,but very useful % Major advantage of this encoded image is like a original image as before encoding. The % image has no visible changes. So no one can easily read the hidden texts by sight. The % decoding logic only can recover the texts. % Thus this special features of encoded image make it used to save the confidential data. % Also can used for web applications, mail services, media etc.,. Can we avoid any one can % read/modify our own data. % %% Tips to use my program: % * For better results images should be in 24-Bit bit map(bmp) format. % * Use larger size image (> 512 X 512) % * Avoid small size Fonts. % * All images should be in the same size. % * Text data should be converted to image format (bmp) before execution. % * Text data should be monochrome(Black letters) ,color text leads to undesire results. % * Change the address of the image mentioned in this program as per your location in % Local drive. % * No need to specify the dimension of the image. %% Part One: Initialize the Input % In this part obtained the input (1 Color image + 6 Text images) from local % drive. Collect all images as a separate variable. Change the location of the image % mentioned in imread() function as per your image. clc; close all; clear all; % Image input im=imread('d:\Documents and Settings\Cherma\Desktop\new\123.bmp');% Color image tx1=imread('d:\Documents and Settings\Cherma\Desktop\new\1.bmp');%Text page 1 tx2=imread('d:\Documents and Settings\Cherma\Desktop\new\2.bmp');%Text page 2 tx3=imread('d:\Documents and Settings\Cherma\Desktop\new\3.bmp');%Text page 3 tx4=imread('d:\Documents and Settings\Cherma\Desktop\new\4.bmp');%Text page 4 tx5=imread('d:\Documents and Settings\Cherma\Desktop\new\5.bmp');%Text page 5 tx6=imread('d:\Documents and Settings\Cherma\Desktop\new\6.bmp');%Text page 6 figure(1); subplot(2,3,1);imshow(tx1);title({'Text to be Encoded';'Page 1'}); subplot(2,3,2);imshow(tx2);title('Page 2'); subplot(2,3,3);imshow(tx3);title('Page 3'); subplot(2,3,4);imshow(tx4);title('Page 4'); subplot(2,3,5);imshow(tx5);title('Page 5'); subplot(2,3,6);imshow(tx6);title('Page 6'); %% Part Two: Image Encoding % In this part the desire text images (max 6 images) are going to encoded with the % Color image. At first pair of text images are combined into a single image. Simple logic % is used to achieve this. Pixels are selected from alternate location of pair of text % images. As a result of this, image having details (but alternate locations) about pair of % two text images. Further explained that if a location (n,m) have the pixel of Image 1 % next location (n+1,m+1) have the pixel taken from Image 2. This task is done by alterim() % function. Two arguments of this function are two text images. % % Next step is to encode the text image which was already obtained from the result % of alterim() function. We obtained 3 single text images from this function. Each image % is encoded in each color frames R,G and B respectively. To do this I used a simple logic. % i.e. encode the text image as a bit of color image LSB. Because LSB bit is very less % significant, so changing this bit won't affect the entire image. Further the text image % is having only black and white area. So I fix a threshold as 128. If a pixel value of a % text image is >128, LSB of Color image is set as '1' otherwise '0'. Simply says if text % is present set that LSB as 1 otherwise 0. Similar way I do it for other two color frames. % All the above operations are performed by imhide() function for each frame % respectively. Arguments of this function are a color frame and a text image obtained % from alterim() function. Finally each frames are added to form a Encoded Water mark % image. % % NOTE: In bmp format each color frame bits are represented by 8-bits. We took the LSB of % that 8-bit. tx1=alterim(tx1,tx2);% Text images 1 & 2 tx2=alterim(tx3,tx4);% Text images 3 & 4 tx3=alterim(tx5,tx6);% Text images 5 & 6 % Hide the text image in color image R(:,:,1)=imhide(im(:,:,1),tx1); R(:,:,2:3)=0;% Text images 1 & 2 in R frame G(:,:,2)=imhide(im(:,:,2),tx2); G(:,:,1:2:3)=0;% Text images 3 & 4 in G frame B(:,:,3)=imhide(im(:,:,3),tx3); B(:,:,1:2)=0;% Text images 5 & 6 in B frame temp=R+G+B; figure(2);subplot(1,2,1); imshow(im); title({'Color image';'(Before Encoding)'}); figure(2);subplot(1,2,2); imshow(uint8(temp)); title({'Watermarked image';'(After Encoding)'}); %% Part Three: Recovery of Text image % In this part two functions are used to recover the text image from Encoded image. % First step is to extract the text image. Remember that text image encoded in the % color image in each frame is the alternate combination of two images (Text). The % function txtxtract() just extract the text image which is the combination of two % text images, not by separate. As we encode our data in LSB of each color frame that % bit alone sufficient to reconstruct our text image. So logical AND operation is % used to recover the LSB. Reverse operation of function imhide() is used to reconstruct % the text. Next step is to separate the pair of two text images from the result of function % txtxtract(). Alternate selection used in previous Encoding section is used again for all % pair of images. R=txtxtract(temp(:,:,1));% Recover text image 1 & 2 from R frame G=txtxtract(temp(:,:,2));% Recover text image 3 & 4 from G frame B=txtxtract(temp(:,:,3));% Recover text image 5 & 6 from B frame [tx1 tx2]=imxtract(R);% Collect pixels from alternate locations [tx3 tx4]=imxtract(G);% Collect pixels from alternate locations [tx5 tx6]=imxtract(B);% Collect pixels from alternate locations %% Part Four: Edge tappering % This part is the final step in my program. The images obtained from previous % step is not a tappered. So finally all text images are smoothen by using % fspecial() function available in MATLAB. PSF = fspecial('laplacian'); figure(3); subplot(2,3,1);imshow(medfilt2(edgetaper(tx1,PSF)));title({'Extracted Text';'Page 1'}); subplot(2,3,2);imshow(medfilt2(edgetaper(tx2,PSF)));title('Page 2'); subplot(2,3,3);imshow(medfilt2(edgetaper(tx3,PSF)));title('Page 3'); subplot(2,3,4);imshow(medfilt2(edgetaper(tx4,PSF)));title('Page 4'); subplot(2,3,5);imshow(medfilt2(edgetaper(tx5,PSF)));title('Page 5'); subplot(2,3,6);imshow(medfilt2(edgetaper(tx6,PSF)));title('Page 6');