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  1. //The code assumes that the image supplied to the program has another image hidden in the lower four bits of each pixel\'s 8 bits.
  2. var image = new SimpleImage("someImage.png");
  3. print(image);
  4. print("Extracting the hidden image now ...");
  5. var extractedImage = extract(image);
  6. print(extractedImage);
  7.  
  8. function extract(imageWithInImage){
  9.     var extractedImage = new SimpleImage(imageWithInImage.getWidth(), imageWithInImage.getHeight());
  10.     for(var pixel of extractedImage.values()){
  11.         var x = pixel.getX();
  12.         var y = pixel.getY();
  13.         var imageWithInImagePixel = imageWithInImage.getPixel(x, y);
  14.         var red = getLowerFourBits(imageWithInImagePixel.getRed());
  15.         var green = getLowerFourBits(imageWithInImagePixel.getGreen());
  16.         var blue = getLowerFourBits(imageWithInImagePixel.getBlue());
  17.         pixel.setRed(red);
  18.         pixel.setGreen(green);
  19.         pixel.setBlue(blue);
  20.     }
  21.     return extractedImage;
  22. }
  23.  
  24. function getLowerFourBits(pixelValue){
  25.     //return (pixelValue * 16) % 256;
  26.     return pixelValue % 16 * 16;
  27. }
');