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POHiding message in JPG image
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  1. POHiding message in JPG image
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    copied!<p>I am trying to hide a in an image it's working fine with .bmp &amp; .png but when I write image as JPG and try to retrieve the hidden message it is not working. My procedure, first read an image in format (<code>bmp</code>, <code>gif</code>, <code>jpg</code>,<code>png</code>) write message to hide and save it so that we can again read it and extract the message. When i save it with <code>bmp</code> or <code>png</code> it works fine but when saving with <code>jpg</code> and try to extract the message it doesn't work.</p> <pre><code> ImageIO.write(bimg, "png", outputfile);//working ImageIO.write(bimg, "png", outputfile);//not working </code></pre> <p>What should I do to make it work for JPEG?</p> <p><strong>note:</strong> I am reading every pixel as 4 bit integer with ARGB value and changing LSB of R,G,B to hide message.</p> <pre><code> public void stegnography(BufferedImage bimg,String msg,String filename) { int w=bimg.getWidth(); int h=bimg.getHeight(); //*************************************** // String msg="Hide this message:)"; System.out.println("message="+msg+" length="+msg.length()); //*************************************** if(msg.length()&gt;255 ) { jLabel3.setText("MESSAGE IS LARGE THAN 255 CHARACTERS"); } else if( msg.length()*11 &gt;w*h) { jLabel3.setText("Image is too small"); } else{ //------------------------------------------- byte[] msgbytes= msg.getBytes(); int msglendecode= (bimg.getRGB(0,0)&gt;&gt;8)&lt;&lt;8; msglendecode |= msg.length(); bimg.setRGB(0, 0,msglendecode );//hidig msg length at first position //System.out.println("\npixel at position (0,0) "); // bitpattern(bimg.getRGB(0,0) ); for(int i=1,msgpos=0,row=0,j=0; row&lt;h ;row++ ) { for(int col=0;col&lt;w &amp;&amp; j&lt;msgbytes.length ;col++,i++ ) { if (i%11==0) { int rgb = bimg.getRGB(col,row); int a=((rgb &gt;&gt; 24) &amp; 0xff); int r = (((rgb &gt;&gt; 16) &amp; 0xff)&gt;&gt;3)&lt;&lt;3; r=r|(msgbytes[msgpos]&gt;&gt;5); int g = (((rgb &gt;&gt; 8) &amp; 0xff)&gt;&gt;3)&lt;&lt;3; g=g|((msgbytes[msgpos]&gt;&gt;2)&amp; 7); int b = ((rgb &amp; 0xff)&gt;&gt;2)&lt;&lt;2; b=b|(msgbytes[msgpos]&amp;0x3); rgb=0; rgb=(rgb|(a&lt;&lt;24)); rgb=(rgb|(r&lt;&lt;16)); rgb=(rgb|(g&lt;&lt;8)); rgb=(rgb|b); bimg.setRGB(col,row,rgb); msgpos++; j++; //bitpattern(bimg.getRGB(col,row)); } }//for 2 }//for 1 ImageIcon image = new ImageIcon(bimg); jLabel3.setIcon(image); try { // File outputfile = new File("c:/Users/yathestha/Documents/"+filename); File outputfile = new File("c:/Users/yathestha/Documents/outpng.png"); ImageIO.write(bimg, "png", outputfile); } catch (IOException e) { System.out.println("error in saving image "); } //------------------------------------------------- }//else // decoding part---------------------------------------------------------------------- } /////////////////////////////////////////////////////////////////////// private void decodestegnography(BufferedImage bimg) { System.out.println("in decode"); int w=bimg.getWidth(),h=bimg.getHeight(); bitpattern(bimg.getRGB(0, 0)); int msglength=(bimg.getRGB(0, 0)&amp;0xff); bitpattern(msglength); System.out.println("Message Length="+msglength); jTextField1.setText(""); for(int row=0,j=0,i=1; row&lt;h ;row++ ) { for(int col=0;col&lt;w &amp;&amp; j&lt;msglength ;col++ ,i++) { if (i%11==0) { int result=bimg.getRGB(col,row); int charatpos = (((result &gt;&gt; 16) &amp; 0x7) &lt;&lt; 5); charatpos |= (((result &gt;&gt; 8) &amp; 0x7) &lt;&lt; 2); charatpos |= ((result &amp; 0x3)); jTextField1.setText(jTextField1.getText()+ (char)charatpos); j++; } } } System.out.println("decoding done"); }//function </code></pre>
 

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