Develop Reference

Pixel relocation, showing side-by-side

I want to read individual pixels from one image and "relocate" them to another image. I basically want to simulate how it would be if I grabbed pixel by pixel from one image and "move" them to a blank canvas. Turning the pixels I grab from the original image white.
This is what I have right now, I'm able to read the pixels from the image and create a copy (which comes out saturated for some reason) of it.
import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ImageTest
{
public static void main(String args[])throws IOException
{
//create buffered image object img
File oldImgFile = new File("/path/to/image/shrek4life.jpg");
BufferedImage oldImg = null;
BufferedImage newImg = null;
try{
oldImg = ImageIO.read(oldImgFile);
}catch(IOException e){}
newImg = new BufferedImage(oldImg.getWidth(), oldImg.getHeight(), BufferedImage.TYPE_INT_ARGB);
File f = null;
try
{
for(int i = 0; i < oldImg.getWidth(); i++){
for(int j = 0; j < oldImg.getHeight(); j++){
//get the rgb color of the old image and store it the new
Color c = new Color(oldImg.getRGB(i, j));
int r = c.getRed();
int g = c.getGreen();
int b = c.getBlue();
int col = (r<<16) | (g<<8) | b;
newImg.setRGB(i, j, col);
}
}
//write image
f = new File("newImg.jpg");
ImageIO.write(newImg, "jpg", f);
}catch(IOException e){
System.out.println("Error: " + e);
}
}//main() ends here
}//class ends here
And I would like to basically slow the process down and display it happening. But I'm not sure how to do that. Would I need to use to accomplish this ? I'm somewhat new to threading but I think I would need multiple threads to handle the painting of both pictures.

First of all, I would like to mention you are working in a very inefficient way. You are creating a Color, decomposing a pixel in its channels, and moving to the new image by a bit-shift. It is easier if you work directly with the integer the whole time (and more efficient).
I will assume the image "/path/to/image/shrek4life.jpg" has ARGB color space. I recommend ensure this, because if the old image does not have this color space you should make a conversion.
When you create the new image, you create it as ARGB color space, so each channel is expressed in a byte of the int, first byte for Alpha, second byte for red, third byte for green and the last one for blue.
I think you forgot the alpha channel when you manipulated the old image pixel to move it into the new image.
With this explanation in mind, I think you can change your code to increase the efficiency, like this:
for(int i = 0; i < oldImg.getWidth(); i++){
for(int j = 0; j < oldImg.getHeight(); j++){
int pixel = oldImg.getRGB(i,j);
newImg.setRGB(i, j, pixel );
//If you like to get more control over the pixels and print
//you can decompose the pixel using Color as you already do
//But when you understand fully the process I recommend erase it
Color c = new Color(pixel);
//Print the color or do whatever you like
}
}
About how to display the process of pixel relocation:
In process:
You can print the changed pixel as a number with its position in image (discouraged). System.out.println("pixel"+pixel+" X:"+i+" Y:"+j);
Use this tutorial in baeldung to print an image. I suggest draw a rectangle with the color of the image and wait for a key press (enter, for example) using Scanner. After the key was press, you can load the next pixel, an so on.
If a single rectangle with just one pixel has little information, I suggest add an array of rectangles to draw several pixels in a time. Even you can print an image, and see the process pixel by pixel, using Scanner to mark each step.
As #haraldK suggest, you can use Swing to display de relocation image. Through swing timer and invokes update()
Post process:
Save the image in a file. To improve the speed of process, I suggest save a few pixels (10 - 100).

java - how to make an image using setRGB?

i have 2D array to keep color component value :
p[pixel_value][red]
p[pixel_value][green]
p[pixel_value][blue]
i just dont know how to use them to make an image.
i read about setRGB, what i understand is i should mix all of them to become a RGBArray. then how to make it?
is it any better way to make an image without setRGB ? i need some explanation.

The method setRGB() can be used to set the color of a pixel of an already existing image. You can open an already existing image and set all the pixels of it, using the values stored in your 2D array.
You can do it like this:
BufferedImage img = ImageIO.read(new File("image which you want to change the pixels"));
for(int width=0; width < img.getWidth(); width++)
{
for(int height=0; height < img.getHeight(); height++)
{
Color temp = new Color(p[pixel_value][red], p[pixel_value][green], p[pixel_value][blue]);
img.setRGB(width, height, temp.getRGB());
}
}
ImageIO.write(img, "jpg", new File("where you want to store this new image"));
Like this, you can iterate over all the pixels and set their color accordingly.
NOTE: By doing this, you will lose your original image. This is just a way which I know.

What you need is a BufferedImage. Create a BufferedImage of type TYPE_3BYTE_BGR, if RGB is what you want, with a specified width and height.
QuickFact:
The BufferedImage subclass describes an Image with an accessible
buffer of image data.
Then, call the getRaster() method to get a WritableRaster
QuickFact:
This class extends Raster to provide pixel writing capabilities.
Then, use the setPixel(int x, int y, double[] dArray) method to set the pixels.
Update:
If all you want is to read an image, use the ImageIO.read(File f) method. It will allow you to read an image file in just one method call.
Somewhat SSCCE:
BufferedImage img = null;
try {
img = ImageIO.read(new File("strawberry.jpg"));
} catch (IOException e) {
}

You want to manually set RGB values?
You need to know that since an int is 32bit it contains all 4 rgb values (1 for the transparency).
xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
^Alpha ^red ^green ^blue
You can accomplish using 4 int values by the use of binary arithmetic:
int rgb = (red << 16) && () (green << 8) & (blue);
bufferedImage.setRGB(x, y, rgb);
IN the above you can add Alpha as well if needed. You just "push" the binary codes into the right places.

Steganography Lsb information hold capacity

I know that using LSB means that u can store messages at around 12% of the image carrier size.
I made a java program that splits a message into n fragments and fills the image carrier with these fragments until the 12 % are all occupied.I do this so that by cropping the image,the message wouldn't get lost.
The problem is that the resulting image is distorted and different from the original image.I thought that if I fill only 12% of the image,more exactly the LSB of the image,the image wouldn't get distorted.
int numHides = imLen/(totalLen*DATA_SIZE); // the number of messages I can store in the image
int offset = 0;
for(int h=0; h < numHides; h++) //hide all frags, numHides times
for(int i=0; i < NUM_FRAGS; i++) {//NUM_FRAGS ..the number of fragments
hideStegoFrag(imBytes, stegoFrags[i], offset);//the method that hides the fragment into the picture starting at the offset position
offset += stegoFrags[i].length*DATA_SIZE;
}
private static boolean hideStegoFrag(byte[] imBytes,byte[] stego,int off){
int offset=off;
for (int i = 0; i < stego.length; i++) { // loop through stego
int byteVal = stego[i];
for(int j=7; j >= 0; j--) { // loop through 8 bits of stego byte
int bitVal = (byteVal >>> j) & 1;
// change last bit of image byte to be the stego bit
imBytes[offset] = (byte)((imBytes[offset] & 0xFE) | bitVal);
offset++;
}
}
return true;
}
The code for transforming the Buffered Image into bits
private static byte[] accessBytes(BufferedImage image)
{
WritableRaster raster = image.getRaster();
DataBufferByte buffer = (DataBufferByte) raster.getDataBuffer();
return buffer.getData();
}
The code that creates the new image with a provided name and the buffered image of the source image
public static boolean writeImageToFile(String imFnm , BufferedImage im){
try {
ImageIO.write(im, "png", new File(imFnm));
} catch (IOException ex) {
Logger.getLogger(MultiSteg.class.getName()).log(Level.SEVERE, null, ex);
}
return true;
}

The output image you have posted is a 16-color paletted image.
The data I am seeing shows that you have actually applied your changes to the palette index, not to the colors of the image. The reason you are seeing the distortion is because of the way the palette is organized, you aren't modifying the LSB of the color, you're modifying the LSB of the index, which could change it to a completely different (and very noticeable, as you can see) color. (Actually, you're modifying the LSB of every other index, the 16-color form is 4 bits per pixel, 2 pixels per byte.)
It looks like you loaded raw image data and didn't decode it in to RGB color information. Your algorithm will only work on raw RGB (or raw grayscale) data; 3 bytes (or 1 for grayscale) per pixel. You need to convert your image to RGB888 or something similar before you operate on it. When you save it, you need to save it in a lossless, full color (unless you actually can fit all your colors in a palette) format too, otherwise you risk losing your information.
Your problem actually doesn't lie in the steganography portion of your program, but in the loading and saving of the image data itself.
When you load the image data, you need to convert it to an RGB format. The most convenient format for your application will be BufferedImage.TYPE_3BYTE_BGR, which stores each pixel as three bytes in blue, green, red order (so your byte array will be B,G,R,B,G,R,B,G,R,...). You can do that like so:
public static BufferedImage loadRgbImage (String filename) {
// load the original image
BufferedImage originalImage = ImageIO.read(filename);
// create buffer for converted image in RGB format
BufferedImage rgbImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
// render original image into buffer, changes to destination format
rgbImage.getGraphics().drawImage(originalImage, 0, 0, null);
return rgbImage;
}
If you are frequently working with source images that are already in BGR format anyways, you can make one easy optimization to not convert the image if it's already in the format you want:
public static BufferedImage loadRgbImage (String filename) {
BufferedImage originalImage = ImageIO.read(filename);
BufferedImage rgbImage;
if (originalImage.getType() == BufferedImage.TYPE_3BYTE_BGR) {
rgbImage = originalImage; // no need to convert, just return original
} else {
rgbImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
rgbImage.getGraphics().drawImage(originalImage, 0, 0, null);
}
return rgbImage;
}
You can then just use the converted image for all of your operations. Note that the byte array from the converted image will contain 3 * rgbImage.getWidth() * rgbImage.getHeight() bytes.
You shouldn't have to make any changes to your current image saving code; ImageIO will detect that the image is RGB and will write a 24-bit PNG.

Is there a function to sum the rasters of two buffered images?

I'm doing 2D filteing and want to do element by element addition on grayscale BufferedImages. Is there an existing function that will complete this for me or do i need to make one from scrach?
Is there some sort of matrix class that converts a raster to a matrix to simplyfy this problem?
Edit: here is the general gist of it
BufferedImageOp opX = new ConvolveOp(new Kernel(3,3, kernelX));
BufferedImageOp opY = new ConvolveOp(new Kernel(3,3, kernelY));
BufferedImage filtImageX = opX.filter(sourceImage, null);
BufferedImage filtImageY = opY.filter(sourceImage, null);
BufferedImage outputImage = addBufferedImages(filtImageX, filtImageY);
Grayscale Conversion:
public void toGrayscale() {
BufferedImageOp op = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
sourceImage = op.filter(sourceImage, null);
}

I am not familiar with any java libs that do that for you.
You can get pixel at [i,j] with: image.getRGB(i, j);
BufferedImage image = ...;
BufferedImage resultImage = ...
int rgb= image.getRGB(i, j);
resultImage.setRGB(i, j, rgb);
You can also convert a buffered image to a byte array [ https://stackoverflow.com/a/7388025/1007845 ].
See this thread: how to convert image to byte array in java? to get a WritableRaster
EDIT:
It seems that WritableRaster might be useful in this case: http://docs.oracle.com/javase/1.4.2/docs/api/java/awt/image/WritableRaster.html
WritableRaster raster = image.getRaster();
for(int h=0;h<height;h++) {
for(int w=0;w<width;w++) {
int colour = 127;
raster.setSample(w,h,0,colour);
}
}

I don't know of a direct way to do this.
But i can suggest a slightly underhanded approach. First, take your two images, and combine them into a single image with two bands. I'm hazy on the details of how to do this. I suspect you will want to create a Raster with a BandedSampleModel, and then blit the contents of the other two images into its DataBuffer. Although it looks like you should be able to create a two-bank DataBuffer which uses the arrays of the source images' (one-banked) DataBuffers as banks, which would avoid copying.
Once you have a two-band image, simply apply a BandCombineOp which sums the bands. You will need to express the summation as a matrix, but that shouldn't be hard. I think it would be [1.0, 1.0],or [0.5, 0.5] if you want to rescale the result.

Java 2D and resize

I have some old Java 2D code I want to reuse, but was wondering, is this the best way to get the highest quality images?
public static BufferedImage getScaled(BufferedImage imgSrc, Dimension dim) {
// This code ensures that all the pixels in the image are loaded.
Image scaled = imgSrc.getScaledInstance(
dim.width, dim.height, Image.SCALE_SMOOTH);
// This code ensures that all the pixels in the image are loaded.
Image temp = new ImageIcon(scaled).getImage();
// Create the buffered image.
BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null),
temp.getHeight(null), BufferedImage.TYPE_INT_RGB);
// Copy image to buffered image.
Graphics g = bufferedImage.createGraphics();
// Clear background and paint the image.
g.setColor(Color.white);
g.fillRect(0, 0, temp.getWidth(null),temp.getHeight(null));
g.drawImage(temp, 0, 0, null);
g.dispose();
// j2d's image scaling quality is rather poor, especially when
// scaling down an image to a much smaller size. We'll post filter
// our images using a trick found at
// http://blogs.cocoondev.org/mpo/archives/003584.html
// to increase the perceived quality....
float origArea = imgSrc.getWidth() * imgSrc.getHeight();
float newArea = dim.width * dim.height;
if (newArea <= (origArea / 2.)) {
bufferedImage = blurImg(bufferedImage);
}
return bufferedImage;
}
public static BufferedImage blurImg(BufferedImage src) {
// soften factor - increase to increase blur strength
float softenFactor = 0.010f;
// convolution kernel (blur)
float[] softenArray = {
0, softenFactor, 0,
softenFactor, 1-(softenFactor*4), softenFactor,
0, softenFactor, 0};
Kernel kernel = new Kernel(3, 3, softenArray);
ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
return cOp.filter(src, null);
}

Chris Campbell has an excellent and detailed write-up on scaling images - see this article.
Chet Haase and Romain Guy also have a detailed and very informative write-up of image scaling in their book, Filthy Rich Clients.

Adding some clarifying information here.
No, that isn't the best way to get a good looking scaled image in Java. Use of getScaledInstance and the underlying AreaAveragingScaleFilter are deprecated by the Java2D team in favor of some more advanced methods.
If you are just trying to get a good-looking thumbnail, using Chris Campbell's method as suggested by David is the way to go. For what it's worth, I have implemented that algorithm along with 2 other faster methods in a Java image-scaling library called imgscalr (Apache 2 license). The point of the library was to specifically address this question in a highly tuned library that is easy to use:
BufferedImage thumbnail = Scalr.resize(srcImg, 150);
To get the best-looking scaled instance possible in Java, the method call would look something like this:
BufferedImage scaledImg = Scalr.resize(img, Method.QUALITY,
150, 100, Scalr.OP_ANTIALIAS);
The library will scale the original image using the incremental-scaling approach recommended by the Java2D team and then to make it look even nicer a very mild convolveop is applied to the image, effectively anti-aliasing it slightly. This is really nice for small thumbnails, not so important for huge images.
If you haven't worked with convolveops before, it's a LOT of work just to get the perfect looking kernel for the op to look good in all use-cases. The OP constant defined on the Scalr class is the result of a week of collaboration with a social networking site in Brazil that had rolled out imgscalr to process profile pictures for it's members. We went back and forth and tried something like 10 different kernels until we found one that was subtle enough not to make the image look soft or fuzzy but still smooth out the transitions between pixel values so the image didn't look "sharp" and noisey at small sizes.
If you want the best looking scaled image regardless of speed, go with Juha's suggestion of using the java-image-scaling library. It is a very comprehensive collection of Java2D Ops and includes support for the Lanczsos algorithm which will give you the best-looking result.
I would stay away from JAI, not because it's bad, but because it is just a different/broader tool than what you are trying to solve. Any of the previous 3 approaches mentioned will give you great looking thumbnails without needing to add a whole new imaging platform to your project in fewer lines of code.

You can use JAI (Java Advanced Imaging) to get more sophisticated image resizing options. See https://jai.dev.java.net/. These allow you much more flexibility than the java.awt.image package.

You could also look into java-image-scaling library.

You can Resize Image using a Open Source Library
enter link description here
I have done with Large Image to Small and result excellent, keeping the aspect ratio fine.
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JOptionPane;
import org.imgscalr.*;
import org.imgscalr.Scalr.Method;
public class ImageScaller {
static String SRC_FILES_PATH = "I:\\BigGreen\\";
static String IMAGE_FILE_PATH = "I:\\Resized\\";
public ImageScaller() {
}
public static void main(String[] args) {
// TODO Auto-generated method stub
try
{
ResizeLoad(SRC_FILES_PATH);
}
catch(Exception ex)
{
System.out.println(ex.toString());
}
}
public static int ResizeLoad(String path)
{
String file;
File folder ;
File[] listOfFiles = null;
listOfFiles = null;
try
{
folder = new File(path);
listOfFiles = folder.listFiles();
for (int i = 0; i < listOfFiles.length; i++)
{
if (listOfFiles[i].isFile())
{
file = listOfFiles[i].getName();
ScalledImageWrite(listOfFiles[i].getPath(),file);
//System.out.println(file);
}
}
System.out.println("All Resized");
}
catch (Exception e)
{
JOptionPane.showMessageDialog(null,e.toString(),"Resize & Load :Exception",JOptionPane.WARNING_MESSAGE);
}
return listOfFiles.length;
}
private static File ScalledImageWrite(String path,String fileName)
{
try
{
BufferedImage img = ImageIO.read(new File(path));
BufferedImage scaledImg = Scalr.resize(img, Method.AUTOMATIC, 24, 24);
File destFile = new File(IMAGE_FILE_PATH + fileName);
ImageIO.write(scaledImg, "png", destFile);
//System.out.println("Done resizing");
return destFile;
}
catch (Exception e)
{
JOptionPane.showMessageDialog(null,e.toString(),"Scalled Images Write: Exception",JOptionPane.WARNING_MESSAGE);
return null;
}
}
}
Here is the output in pictorial format of this code.