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私は以下の問題があります。LSBにメッセージをコーディングして簡単なステガノグラフィ「プログラム」を作成します。ImageWriterは小さな画像を作成します（KBサイズで）
青い色のLSBでメッセージをエンコードし、それらの新しい値を使用して新しいイメージを作成しようとしました（ARGBアレイをint配列に戻します）。
私が持っている明らかな問題は、LSBを変更して画像に書き込もうとすると、ImageWriterの画像がkbで非常に小さくなっていることがわかり、メッセージを引き出すことができなくなります。
これはコードです：
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
public class Steganography {
int [][] alpha;
int [][] red;
int [][] green;
int [][] blue;
public int [][] readPixels (String image) throws IOException {
//load image into img buffer
BufferedImage img = ImageIO.read(new File(image));
//make matrix according to picture height and width
int [][] pixels = new int[img.getHeight()][img.getWidth()];
// load matrix with image pixels
for(int i=0;i<pixels.length;i++) {
for (int j = 0; j < pixels[0].length; j++) {
pixels[i][j]=(img.getRGB(j, i));
}
}
/* reminder to myself
values will be negative because of packing the 4 byte values into a 4-byte
The getRGB method returns an int whose 4 bytes are the alpha, red, green, and blue components in that order.
Assuming that the pixel is not transparent, the alpha is 255 (0xFF).
It's the most significant byte in the int, and the first bit is set in that value.
Because in Java int values are signed according to Two's Complement,
the value is actually negative because that first bit is on.
*/
return pixels ;
}
// extracts colors and alpha into their own matrix so we can reconstruct image later
public void extractColors(int [][] pixel){
this.alpha = new int[pixel.length][pixel[0].length];
this.red = new int[pixel.length][pixel[0].length];
this.green = new int[pixel.length][pixel[0].length];
this.blue = new int[pixel.length][pixel[0].length];
for(int i=0;i<pixel.length;i++) {
for(int j=0;j<pixel[i].length;j++){
int clr = pixel[i][j];
alpha[i][j] = (clr & 0xff000000) >> 24;
red[i][j] = (clr & 0x00ff0000) >> 16;
green[i][j] = (clr & 0x0000ff00) >> 8;
blue [i][j] = clr & 0x000000ff;
}
}
} // closed method
//reconstruct image
// need to make 32 bit integer again in correct order
public void reconstructImage() throws IOException{
int height = alpha.length;
int width= alpha[0].length;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int y = 0; y < width; y++) {
for (int x = 0; x < height; x++) {
int rgb= red[x][y];
rgb = (rgb << 8) + green[x][y];
rgb = (rgb << 8) + blue[x][y];
image.setRGB(y, x, rgb);
}
}
ImageWriter writer = ImageIO.getImageWritersByFormatName("jpeg").next();
ImageWriteParam param = writer.getDefaultWriteParam();
param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); // Needed see javadoc
param.setCompressionQuality(1.0F); // Highest quality
File file = new File("output.jpg");
ImageOutputStream ios = ImageIO.createImageOutputStream(file);
writer.setOutput(ios);
writer.write(image);
}
public void codeMessage (String message){
//first turn string into binary representation
// each character should have 7 bits
// ASCII uses 7 bit
message="START"+message.length()+message+"STOP";
String binaryMessage ="";
for(int i =0;i<message.length();i++){
//adding zeros if string has less than 8 characters
String binaryString= Integer.toBinaryString(message.charAt(i));
while (binaryString.length() !=7)
binaryString = "0"+binaryString;
binaryMessage+=binaryString;
}
//binaryMessage is binary representation of string
// change value of LSB in blue color according to binaryMessage
//actually coding message into LSB is done here
int k=0;
for (int i = 0; i < blue.length; i++) {
for (int j = 0; j < blue[i].length; j++) {
if(k>=binaryMessage.length())
break;
else if (binaryMessage.charAt(k) == '0') {
blue[i][j] = blue[i][j] & 0b1111110;
k++;
}
else {
blue[i][j] = blue[i][j] | 0b0000001;
k++;
}
}
}
} //closed codeMessage
public void readMessage(){
String LSB ="";
char charLSB;
String messageBinary ="";
for(int i=0;i<blue.length;i++){
for(int j=0;j<blue[i].length;j++){
LSB = Integer.toBinaryString(blue[i][j]);
charLSB = LSB.charAt(LSB.length()-1);
messageBinary+=charLSB;
}
}
char ArrayOfChars [] = new char [blue[0].length*blue.length];
int k =0;
for(int i=0;i<messageBinary.length()-7;i+=7){
String letter=(messageBinary.substring(i,i+7));
int valueOfASCIIcharacter = Integer.parseInt(letter,2);
char c = (char)(valueOfASCIIcharacter);
System.out.println(c);
ArrayOfChars[k]=c;
k++;
}
}
}
私も（色のみを台無しに、絵はちょっとピンク取得）運なしで、BufferedImageのために代わりにRGBのARGBを使用しようとしました。
は、これは私が
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException{
Steganography img = new Steganography();
int pixels [][] =img.readPixels("image.jpg");
img.extractColors(pixels);
img.codeMessage("Some message");
img.reconstructImage();
/*reading message from here on */
int pixels2 [][] = img.readPixels("output.jpg");
img.extractColors(pixels2);
img.readMessage();
}
}
オリジナル画像は83,3キロバイトを持っているメインクラス内の関数を呼び出し、再作成画像のみ24,3キロバイトを持っているかです。