fork download
copy 
  1. import java.awt.Color;
  2. import java.awt.image.BufferedImage;
  3. import java.io.File;
  4. import java.io.IOException;
  5. import java.util.Scanner;
  6.  
  7. import javax.imageio.ImageIO;
  8.  
  9. public class EncodeBMP {
  10.  
  11.     public static void main(String[] args) throws IOException {
  12. 		{
  13. 			BufferedImage bi = ImageIO.read(new File("in.bmp"));
  14. 			Color[][] image = new Color[bi.getWidth()][bi.getHeight()];
  15. 			for (int i = 0; i < image.length; i++)
  16. 				for (int j = 0; j < image[i].length; j++) {
  17. 					image[i][j] = new Color(bi.getRGB(i, j));
  18. 				}
  19. 			encodeBMP(image, "data");
  20. 			for (int i = 0; i < image.length; i++)
  21. 				for (int j = 0; j < image[i].length; j++) {
  22. 					bi.setRGB(i, j, image[i][j].getRGB());
  23. 				}
  24. 			ImageIO.write(bi, "bmp", new File("out.bmp"));
  25. 		}
  26. 		{
  27. 			BufferedImage bi = ImageIO.read(new File("out.bmp"));
  28. 			Color[][] image = new Color[bi.getWidth()][bi.getHeight()];
  29. 			for (int i = 0; i < image.length; i++)
  30. 				for (int j = 0; j < image[i].length; j++) {
  31. 					image[i][j] = new Color(bi.getRGB(i, j));
  32. 				}
  33. 			System.out.println(extractMessage(image));
  34. 			System.out.println("--------------------");
  35. 		}
  36. 	}
  37.  
  38. 	// returns byte with last bit modified if necessary
  39. 	private static void modLSB(int[] bytes, int j, char foo) {
  40. 		if (foo == '1')
  41. 			bytes[j] = bytes[j] | 1; // make lsb one
  42. 		else
  43. 			bytes[j] = bytes[j] & ~1; // make lsb zero
  44. 	}
  45.  
  46. 	// loads a text file and inserts it into the current BMP object
  47. 	public static void encodeBMP(Color[][] image, String fName) {
  48. 		String message = "";
  49. 		try {
  50. 			Scanner sc = new Scanner(new File(fName));
  51. 			while (sc.hasNextLine())
  52. 				message += sc.nextLine() + "\n";
  53. 			System.out.println(message);
  54. 			System.out.println("--------------------");
  55. 			sc.close();
  56.  
  57. 			// read all rgb values into a bytes array
  58. 			int[] bytes = new int[image.length * image[0].length * 3];
  59. 			int i = 0;
  60. 			for (Color[] cRow : image)
  61. 				for (Color c : cRow) {
  62. 					bytes[i++] = c.getRed();
  63. 					bytes[i++] = c.getGreen();
  64. 					bytes[i++] = c.getBlue();
  65. 				}
  66.  
  67. 			// modify each value based on the text
  68. 			int j = 0;
  69. 			for (i = 0; i < message.length(); i++) {
  70. 				char c = message.charAt(i);
  71. 				String bin = Integer.toBinaryString((int) c);
  72. 				bin = eightBitsLong(bin);
  73.  
  74. 				modLSB(bytes, j++, bin.charAt(0));
  75. 				modLSB(bytes, j++, bin.charAt(1));
  76. 				modLSB(bytes, j++, bin.charAt(2));
  77. 				modLSB(bytes, j++, bin.charAt(3));
  78. 				modLSB(bytes, j++, bin.charAt(4));
  79. 				modLSB(bytes, j++, bin.charAt(5));
  80. 				modLSB(bytes, j++, bin.charAt(6));
  81. 				modLSB(bytes, j++, bin.charAt(7));
  82. 			}
  83.  
  84. 			// read values back into colors
  85. 			int k = 0;
  86. 			for (i = 0; i < image.length; i++)
  87. 				for (j = 0; j < image[i].length; j++) {
  88. 					image[i][j] = new Color(bytes[k], bytes[k + 1],
  89. 							bytes[k + 2]);
  90. 					k += 3;
  91. 				}
  92. 		} catch (Exception e) {
  93. 			e.printStackTrace();
  94. 			System.exit(0);
  95. 		}
  96. 	}
  97.  
  98. 	private static String eightBitsLong(String str) // recursion!
  99. 	{
  100. 		if (str.length() == 8)
  101. 			return str;
  102. 		else if (str.length() > 8)
  103. 			return eightBitsLong(str.substring(2));
  104. 		else
  105. 			return eightBitsLong("0" + str);
  106. 	}
  107.  
  108. 	// extracts a message hidden in a BMP file
  109. 	public static String extractMessage(Color[][] image) {
  110. 		int iter = 0;
  111. 		// read the lsbs of the rgb values into one array
  112. 		char[] pixels = new char[image.length * image[0].length * 3];
  113. 		for (Color[] cRow : image)
  114. 			for (Color c : cRow) {
  115. 				pixels[iter++] = (char) (c.getRed() & 1); // make zero or one
  116. 				pixels[iter++] = (char) (c.getGreen() & 1);
  117. 				pixels[iter++] = (char) (c.getBlue() & 1);
  118. 			}
  119.  
  120. 		// iterate through the pixels and move the lsbs into the correct place
  121. 		// value
  122. 		String message = "";
  123. 		int i = 0;
  124. 		while (i < pixels.length - pixels.length % 8) {
  125. 			char c = (char) 0;
  126. 			c += pixels[i++] << 7; // 1
  127. 			c += pixels[i++] << 6; // 2
  128. 			c += pixels[i++] << 5; // 3
  129. 			c += pixels[i++] << 4; // 4
  130. 			c += pixels[i++] << 3; // 5
  131. 			c += pixels[i++] << 2; // 6
  132. 			c += pixels[i++] << 1; // 7
  133. 			c += pixels[i++]; // 8
  134. 			message += c;
  135. 		}
  136. 		return message;
  137. 	}
  138.  
  139. }
  140.  
Not running #stdin #stdout 0s 0KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
https://ideone.com/I7GXvW
Require files:

1. "in.bmp" A large enough bmp file.
2. "data" A file containing data to hide.

Some unused byte will be padded to the end of output, though.
language:
Java (12.0.1)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!