/**
* Hides the given message inside the specified image.
*
* <p>The image will be given to you as a GImage of some size, and the message will be specified
* as a boolean array of pixels, where each white pixel is denoted false and each black pixel is
* denoted true.
*
* <p>The message should be hidden in the image by adjusting the red channel of all the pixels in
* the original image. For each pixel in the original image, you should make the red channel an
* even number if the message color is white at that position, and odd otherwise.
*
* <p>You can assume that the dimensions of the message and the image are the same.
*
* <p>
*
* @param message The message to hide.
* @param source The source image.
* @return A GImage whose pixels have the message hidden within it.
*/
public static GImage hideMessage(boolean[][] message, GImage source) {
int[][] pixels = source.getPixelArray();
for (int row = 0; row < pixels.length; row++) {
for (int col = 0; col < pixels[row].length; col++) {
/* Extract the green and blue components and write them back, changing the
* red component.
*/
int red = GImage.getRed(pixels[row][col]);
int green = GImage.getGreen(pixels[row][col]);
int blue = GImage.getBlue(pixels[row][col]);
if (message[row][col]) {
if (red % 2 == 0) { // If the secret pixel is black, make the red channel odd
red++;
}
} else {
if (red % 2 != 0) { // If the secret pixel is white, make the red channel even
red++;
}
if (red > 255) {
red -= 2;
}
}
pixels[row][col] = GImage.createRGBPixel(red, green, blue);
}
}
return new GImage(pixels);
}
private static int redToEven(int pixel) { // в НЕЧЕТНЫЙ
int oldRed = GImage.getRed(pixel);
int newRed;
if (oldRed % 2 == 1) { // нечетный
newRed = oldRed;
} else { // если четный
newRed = oldRed + 1;
}
return GImage.createRGBPixel(
newRed, GImage.getGreen(pixel), GImage.getBlue(pixel), GImage.getAlpha(pixel));
}
/**
* Given a GImage containing a hidden message, finds the hidden message contained within it and
* returns a boolean array containing that message.
*
* <p>A message has been hidden in the input image as follows. For each pixel in the image, if
* that pixel has a red component that is an even number, the message value at that pixel is
* false. If the red component is an odd number, the message value at that pixel is true.
*
* @param source The image containing the hidden message.
* @return The hidden message, expressed as a boolean array.
*/
public static boolean[][] findMessage(GImage source) {
int[][] image = source.getPixelArray();
boolean[][] result = new boolean[image.length][image[0].length];
for (int i = 0; i < image.length; i++) {
for (int j = 0; j < image[0].length; j++) {
result[i][j] = ((GImage.getRed(image[i][j]) % 2) != 0);
}
}
return result;
}
/**
* Given a GImage containing a hidden message, finds the hidden message contained within it and
* returns a boolean array containing that message.
*
* <p>A message has been hidden in the input image as follows. For each pixel in the image, if
* that pixel has a red component that is an even number, the message value at that pixel is
* false. If the red component is an odd number, the message value at that pixel is true.
*
* @param source The image containing the hidden message.
* @return The hidden message, expressed as a boolean array.
*/
public static boolean[][] findMessage(GImage source) {
int[][] pixels = source.getPixelArray();
boolean[][] bwImage = new boolean[pixels.length][];
for (int row = 0; row < pixels.length; row++) {
bwImage[row] = new boolean[pixels[row].length];
for (int col = 0; col < pixels[row].length; col++) {
int red = GImage.getRed(pixels[row][col]);
bwImage[row][col] =
red % 2 == 0
? false
: true; // recover the hidden message by returning a boolean[][] containing the
// pixels of the hidden image
}
}
return bwImage;
}
