Develop Reference

Poor performance reading images on java

I've written a small application for personal use in macOs using java (the only language I know) that reads a directory and compare the images found in it with every other image.
Edit: As user dbush pointed out, here is the code I should've posted:
for (int i = 0; i < files.size(); i++) {
file1 = files.get(i).getAbsolutePath();
for (int j = i + 1; j < files.size(); j++) {
file2 = files.get(j).getAbsolutePath();
System.out.println("Comparing " + files.get(i).getName() + sp + files.get(j).getName());
System.out.println(Arrays.equals(extractBytes(file1), extractBytes(file2)));
}
}
private static byte[] extractBytes(String imageName) throws IOException {
// open image
File imgPath = new File(imageName);
BufferedImage bufferedImage = getSample(imgPath);
// get DataBufferBytes from Raster
WritableRaster raster = bufferedImage.getRaster();
DataBufferByte data = (DataBufferByte) raster.getDataBuffer();
return (data.getData());
}
private static BufferedImage getSample(File f) {
BufferedImage img = null;
Rectangle sourceRegion = new Rectangle(0, 0, 10, 10); // The region you want to extract
try {
ImageInputStream stream1 = ImageIO.createImageInputStream(f); // File or input stream
Iterator<ImageReader> readers = ImageIO.getImageReaders(stream1);
if (readers.hasNext()) {
ImageReader reader = readers.next();
reader.setInput(stream1);
ImageReadParam param = reader.getDefaultReadParam();
param.setSourceRegion(sourceRegion); // Set region
img = reader.read(0, param); // Will read only the region specified
}
} catch (IOException e) {
System.out.println(e);
}
return img;
}
It involves reading two images in a byte array and comparing both. The problem is that it takes a long time to do this, even if I sample a small portion of each image.
Should I re-write the same application in C or swift for better performance, considering I'll be running it on macOs from the terminal? Or it will do minimal difference.
Thanks a lot in advance!

Steganography, only jpg as input works, when using png the resulting image looks strange

I built a little java program that hides messages in an image using the least significant bit method. It works fine when inputting a jpg file. The output may be png or jpg. When inputting a png though, the result looks very stange.
Here are the original and the result images respectively:
public abstract class Builder{
public static void leastSignificantBitEncryption(String imageSource, String message, String newPath) {
BufferedImage image = returnImage(imageSource);
//prepare variables
String[] messageBinString = null;
String[] pixelBinString = null;
final byte[] messageBin = message.getBytes(StandardCharsets.UTF_8);
final byte[] pixelsBin = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
//convert message and image to binary string array
try {
messageBinString = stringToBinaryStrings(messageBin);
pixelBinString = stringToBinaryStrings(pixelsBin);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
String[] messageBinStringCut = splitIn2Bit(messageBinString); //split message binary into 2 bit strings
String[] pixelBinStringNew = pixelBinString.clone(); //insert 2 bit strings in last 2 bits of bytes from bitmap
insert2Bit(messageBinStringCut, pixelBinStringNew);
byte[] pixelsBinNew = stringArrayToByteArray(pixelBinStringNew); //Convert string array to byte array
try { //Create new image out of bitmap
int w = image.getWidth();
int h = image.getHeight();
BufferedImage imageNew = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR);
imageNew.setData(Raster.createRaster(imageNew.getSampleModel(), new DataBufferByte(pixelsBinNew, pixelsBinNew.length), new Point()));
File imageFile = new File(newPath);
ImageIO.write(imageNew, "png", imageFile);
} catch (IOException e) {
e.printStackTrace();
}
}
private static String[] stringToBinaryStrings(byte[] messageBin) throws UnsupportedEncodingException{
String[] bytes = new String[messageBin.length];
int i = 0;
for(byte b : messageBin) {
bytes[i] = String.format("%8s", Integer.toBinaryString(b & 0xFF)).replace(' ', '0');
i++;
}
return bytes;
}
private static String binaryStringsToString(String[] messageBin) throws UnsupportedEncodingException{
StringBuilder stringBuilder = new StringBuilder();
int i = 0;
while(messageBin[i] != null) {
stringBuilder.append((char) Integer.parseInt(messageBin[i], 2));
i++;
}
return stringBuilder.toString();
}
private static BufferedImage returnImage(String imageSource) {
try{
try {
return ImageIO.read(new URL(imageSource));
} catch (MalformedURLException e) {
return ImageIO.read(new File(imageSource));
}
} catch (IOException ioe) {
ioe.printStackTrace();
return null;
}
}
private static byte[] stringArrayToByteArray(String[] stringArray) {
byte[] byteArray = new byte[stringArray.length];
for(int i = 0; i < stringArray.length; i++) {
byteArray[i] = (byte) Integer.parseInt(stringArray[i], 2);
}
return byteArray;
}
private static String[] splitIn2Bit(String[] inputArray) {
String[] outputArray = new String[inputArray.length * 4];
for(int i = 0; i < outputArray.length; i += 4) {
String[] splitByte = inputArray[i / 4].split("(?<=\\G..)");
outputArray[i] = splitByte[0];
outputArray[i + 1] = splitByte[1];
outputArray[i + 2] = splitByte[2];
outputArray[i + 3] = splitByte[3];
}
return outputArray;
}
private static String[] insert2Bit(String[] twoBitArray, String[] insertArray) {
for(int i = 0; i < twoBitArray.length; i++) {
insertArray[i] = insertArray[i].substring(0, 6) + twoBitArray[i];
}
return insertArray;
}
}
Also, the testclass:
public class Test {
public static void main(String[] args) {
Builder.leastSignificantBitEncryption("IMAGEPATH OR URL", "MESSAGE", "PATH FOR IMAGE CONTAINING MESSAGE");
Builder.leastSignificantBitDecryption("PATH OF IMAGE CONTAINING MESSAGE", "PATH FOR TXT CONTAINING OUTPUT");
}
}

The error originates from the fact that the png image has an extra channel for transparency. System.out.println(pixelsBin.length); returns 338355 bytes for the jpg and 451140 bytes for the png.
The simplest solution would be to create the appropriate imageNew depending on the format file. For example,
int w = image.getWidth();
int h = image.getHeight();
BufferedImage imageNew = null;
if (imageSource.matches(".*jpg$")) {
imageNew = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR);
} else if (imageSource.matches(".*png$")) {
imageNew = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR);
} else {
// whatever
}
imageNew.setData(Raster.createRaster(imageNew.getSampleModel(), new DataBufferByte(pixelsBinNew, pixelsBinNew.length), new Point()));
However, you have to be aware that the message is not embedded in both types in the same pixels. The byte array of a 3-channel image (no transparency) goes like this
first-pixel-BLUE, first-pixel-GREEN, first-pixel-RED, second-pixel-BLUE, etc
while for a 4-channel image
first-pixel-ALPHA, first-pixel-BLUE, first-pixel-GREEN, first-pixel-RED, second-pixel-ALPHA, etc
If you care about that detail, you might be interested in removing the alpha channel from the png first, so you're always working with 3-channel images.

Cant use setRGB() to write to png

public static void main(String[] args) {
String finalHex = "";
String input = "Hello There Sir.";
int pixelX = -1;
int pixelY = 0;
try{
BufferedImage bi = new BufferedImage(64, 64, BufferedImage.TYPE_INT_ARGB);
File out = new File("saved.png");
if(out.exists()==false){
ImageIO.write(bi, "png", out);
System.out.println("PNG WAS CREATED");
}else
System.out.println("ERROR: PNG WAS ALREADY THERE");
for (int i = 0;i < input.length(); i++){
char result = input.charAt(i);
int ascii = (int) result;
String num = Integer.toHexString(ascii).toUpperCase();
if(finalHex.length()==6){
System.out.println(finalHex);
pixelX += 1;
finalHex=("#"+finalHex);
Color c = Color.decode(finalHex);
int rgb = c.getRGB();
System.out.println(rgb);
if(pixelX==63){
pixelX=0;
pixelY+=1;
}
bi.setRGB(pixelX, pixelY, rgb);
finalHex="";
}
finalHex+=num;
}
}catch(IOException e){
System.out.println("ERROR: WELP... SOMETHING SCREWED UP.");
}
}
I am trying to use this to convert text into a png image but I cant get it to write to a png file. I am not that experienced in this area so if anyone could help me out i would be very much appreciated. :)

you should add ImageIO.write(bi, "png", out); after the end of for(int i = 0;i < input.length(); i++){...} this program will write some colored pixels is that what you want??
example:
result picture

Combining PNG Images Java

I am trying to loop through a file of png images and stitch them together to form one image. I have gotten it to work without using a for loop and just combining two images from the file. So I am assuming it is the looping that isn't working. The images are located in a file called "images".
I would appreciate your input!
File file = new File("images");
File [] moreFile = file.listFiles();
String [] images = new String [moreFile.length];
for(int i =0; i <images.length; i++)
{images[i] = moreFile[i].getName();
}
int x = 0;
int y = 0;
BufferedImage result = new BufferedImage(
controller.getSize().width*2, controller.getSize().height, //work these out
BufferedImage.TYPE_INT_RGB);
Graphics g = result.getGraphics();
for(String image : images){
System.out.println(image);
File path = new File("images");
try{ImageIO.read(new File(path, image));
System.out.println("it definitely goes here");
BufferedImage bi = new BufferedImage((2*510),(2*439),BufferedImage.TYPE_INT_ARGB);
bi =ImageIO.read(new File(path, image));
g.drawImage(bi, x, y, null);
g.dispose();
/// System.out.println(dafuck);
x += bi.getWidth();
if(x > result.getWidth()){
x = 0;
y += bi.getHeight();
}
}catch (Exception e) {
System.out.println("is it an exception>?");
}
}
try {
ImageIO.write(result,"png",new File("results"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Java exception "Exception in thread "main" java.lang.ClassCastException: [B cannot be cast to [I" when calling java.awt.image.BufferedImage.copyData()

In the following code, I'm trying to combine some 1024*1024 png into several larger pngs. The code fails with this exception:
Exception in thread "main" java.lang.ClassCastException: [B cannot be cast to [I
at sun.awt.image.IntegerInterleavedRaster.setDataElements(Unknown Source)
at java.awt.image.BufferedImage.copyData(Unknown Source)
at mloc.bs12.mapimagemerger.Merger.main(Merger.java:27)
It's probably something small and silly which I overlooked, but I can't find anything wrong with the code.
Code:
import java.awt.image.*;
import javax.imageio.*;
import java.io.*;
public class Merger {
public static void main(String[] args) {
String toX, toY, toZ;
try {
toX = args[0];
toY = args[1];
toZ = args[2];
} catch(ArrayIndexOutOfBoundsException E) {
//E.printStackTrace();
toX = "3";
toY = "5";
toZ = "4";
}
int yproper = 1;
for(int z = 1; z <= Integer.parseInt(toZ); z++) {
BufferedImage img = new BufferedImage(Integer.parseInt(toX) * 1024, Integer.parseInt(toY) * 1024, BufferedImage.TYPE_INT_RGB);
for(int x = 1; x <= Integer.parseInt(toX); x++) {
for(int y = 1; y <= Integer.parseInt(toY); y++) {
BufferedImage simg = img.getSubimage(x*1024, y*1024, 1024, 1024);
BufferedImage tempimg = loadImage(x + "-" + y + "-" + z + ".png");
WritableRaster rsimg = simg.getRaster();
rsimg = tempimg.copyData(rsimg); <-- Error!
yproper++;
}
}
saveImage(img, z + ".png");
}
}
public static BufferedImage loadImage(String path) {
BufferedImage bimg = null;
try {
bimg = ImageIO.read(new File(path));
} catch (Exception e) {
e.printStackTrace();
}
return bimg;
}
public static void saveImage(BufferedImage img, String path) {
try {
ImageIO.write(img, "png", new File(path));
} catch (Exception e) {
e.printStackTrace();
}
return;
}
}
I think I have this figured out by now.
The images I was loading were not the same type as the image I created. (I'm still not sure what type they are, what is the 13 type?)
I have some more problems, but this error is fixed.
(More problems, as in this.)

The library casts a byte array to an int array, which you cannot do.
I am unfamiliar with BufferedImage but a qualified guess would be that the PNG file you read in, is treated as byte values instead of integer values.