Develop Reference

java croped image all black

I am trying to crop an image using a java, here is my code:
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class crop
{
public static void main(String[] args)
{
BufferedImage img = null;
try
{
img = ImageIO.read(new File("/Users/mathewlewis/desktop/pic.jpg"));
String width = "" + img.getWidth();
String height = "" + img.getHeight();
cout("heigth = " + height + " and width = " + width);
BufferedImage crp = img.getSubimage(0,0,100,200);
try {
File outputfile = new File("crop_pic.jpg");
ImageIO.write(crp, "jpg", outputfile);
}
catch (IOException e)
{
System.out.println("error");
}
}
catch (IOException e)
{
System.out.println("error");
}
}
}
Everything runs fine (no errors), but when I open crop_pic.jpg it is all black. Here is pic.jpg.
I would like to know why the image comes out all black, and how I can fix it.
I tried this
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class crop
{
public static void main(String[] args)
{
BufferedImage img = null;
try
{
img = ImageIO.read(new File("/Users/mathewlewis/desktop/pic.jpg"));
BufferedImage rgbImage = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
ColorConvertOp op = new ColorConvertOp(null);
op.filter(img, rgbImage);
BufferedImage crp = rgbImage.getSubimage(300,300,rgbImage.getWidth()-300,rgbImage.getHeight()-300);
try {
File outputfile = new File("crop_pic.jpg");
ImageIO.write(crp, "jpg", outputfile);
}
catch (IOException e)
{
System.out.println("error");
}
}
catch (IOException e)
{
System.out.println("error");
}
}
}
and got this error:
crop.java:16: error: cannot find symbol
ColorConvertOp op = new ColorConvertOp(null);
^
symbol: class ColorConvertOp
location: class crop
crop.java:16: error: cannot find symbol
ColorConvertOp op = new ColorConvertOp(null);
^
symbol: class ColorConvertOp
location: class crop
2 errors
Thank you Forseth11!! should have noticed that I didn't import java.awt.image.ColorConvertOp! You've been a great help. Thanks a lot!!!

I looked around a bit and found that other people have had a similar problem. On my end when testing this I got a strangely colored image, not a black image. This problem is caused because ImageIO is reading the image wrong.
Here is what I have come up with which works, but since I could not replicate your problem and get a black image this may not work for you.
img = ImageIO.read(new File("/Users/mathewlewis/desktop/pic.jpg"));
BufferedImage rgbImage = new BufferedImage(img.getWidth(), img.getHeight(),
BufferedImage.TYPE_3BYTE_BGR);
ColorConvertOp op = new ColorConvertOp(null);
op.filter(img, rgbImage);
String width = "" + rgbImage.getWidth();
String height = "" + rgbImage.getHeight();
System.out.println("heigth = " + height + " and width = " + width);
BufferedImage crp = rgbImage.getSubimage(300,300,rgbImage.getWidth()-300,rgbImage.getHeight()-300);
These are some other posts which have a similar issue:
jpeg image color gets drastically changed after just ImageIO.read() and ImageIO.write()
Unable to read JPEG image using ImageIO.read(File file)
Edit: I changed where it cropped, so it is easy to see because the upper left part of the image is mostly yellow.

Take picture using webcam in netbeans java?

I have been busy with trying to get the webcam to work within netbeans over the past few days.
The problem I am having is to get the coding to activate and take a picture using the webcam.
So far I have seen that I will have to use the OpenCV and some other JAR files.
Please could someone help me out by perfecting the coding I have below:
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// coding for webcam and taking a picture
OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0);
try
{
//start of the webcam for taking the picture
grabber.start();
Image IM = this.takePicture();
//stops the webcam
grabber.stop();
}
catch (Exception e)
{
//displays error message if problem with webcam
JOptionPane.showMessageDialog(null, "Problem accessing or using the Webcam!");
}
}
What I need is for the picture to be displayed in a label on my interface after it has taken the picture.
The Open CV has been successfully installed and now just the coding needed to get the picture taken.
Any Help would be helpful.

Okay, your coding is a bit off, it does need some changes made to it. You are on the right track however.
I do have a sample code that may be able to help you out which works:
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
// coding for webcam and taking a picture
OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0);
try
{
//start of the webcam for taking the picture
grabber.start();
//grabs teh image taken from the webcam
IplImage img = grabber.grab();
//checks if the webcam has taken the picture and if the picture if mot empty
if(img != null)
{
//determines where to save the picture
cvSaveImage("C:\\User1\\PrifilePicture\\"+lbl_StudnetLogin.getText()+".jpeg", img);
}
//stops the webcam
grabber.stop();
//used to resize teh picture taken in order to display picture to the user
Image imeResize = ImageIO.read(new File("C:\\SalVentri\\PrifilePicture\\"+lbl_StudnetLogin.getText()+".jpeg"));
//1st ---> width _______2sn ---> height
lbl_Profile.setIcon(new ImageIcon(imeResize.getScaledInstance(155, 100, 100)));
}
catch (Exception e)
{
//displays error message if problem with webcam
JOptionPane.showMessageDialog(null, "Problem accessing or using the Webcam!");
}
}
Hope this helps

I found that this works as well.
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.awt.image.WritableRaster;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.opencv.core.*;
import org.opencv.highgui.Highgui;
import org.opencv.highgui.VideoCapture;
public class JPanelOpenCV extends JPanel{
BufferedImage image;
public static void main (String args[]) throws InterruptedException{
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
JPanelOpenCV t = new JPanelOpenCV();
VideoCapture camera = new VideoCapture(0);
Mat frame = new Mat();
camera.read(frame);
if(!camera.isOpened()){
System.out.println("Error");
}
else {
while(true){
if (camera.read(frame)){
BufferedImage image = t.MatToBufferedImage(frame);
t.window(image, "Original Image", 0, 0);
t.window(t.grayscale(image), "Processed Image", 40, 60);
//t.window(t.loadImage("ImageName"), "Image loaded", 0, 0);
break;
}
}
}
camera.release();
}
#Override
public void paint(Graphics g) {
g.drawImage(image, 0, 0, this);
}
public JPanelOpenCV() {
}
public JPanelOpenCV(BufferedImage img) {
image = img;
}
//Show image on window
public void window(BufferedImage img, String text, int x, int y) {
JFrame frame0 = new JFrame();
frame0.getContentPane().add(new JPanelOpenCV(img));
frame0.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame0.setTitle(text);
frame0.setSize(img.getWidth(), img.getHeight() + 30);
frame0.setLocation(x, y);
frame0.setVisible(true);
}
//Load an image
public BufferedImage loadImage(String file) {
BufferedImage img;
try {
File input = new File(file);
img = ImageIO.read(input);
return img;
} catch (Exception e) {
System.out.println("erro");
}
return null;
}
//Save an image
public void saveImage(BufferedImage img) {
try {
File outputfile = new File("Images/new.png");
ImageIO.write(img, "png", outputfile);
} catch (Exception e) {
System.out.println("error");
}
}
//Grayscale filter
public BufferedImage grayscale(BufferedImage img) {
for (int i = 0; i < img.getHeight(); i++) {
for (int j = 0; j < img.getWidth(); j++) {
Color c = new Color(img.getRGB(j, i));
int red = (int) (c.getRed() * 0.299);
int green = (int) (c.getGreen() * 0.587);
int blue = (int) (c.getBlue() * 0.114);
Color newColor =
new Color(
red + green + blue,
red + green + blue,
red + green + blue);
img.setRGB(j, i, newColor.getRGB());
}
}
return img;
}
public BufferedImage MatToBufferedImage(Mat frame) {
//Mat() to BufferedImage
int type = 0;
if (frame.channels() == 1) {
type = BufferedImage.TYPE_BYTE_GRAY;
} else if (frame.channels() == 3) {
type = BufferedImage.TYPE_3BYTE_BGR;
}
BufferedImage image = new BufferedImage(frame.width(), frame.height(), type);
WritableRaster raster = image.getRaster();
DataBufferByte dataBuffer = (DataBufferByte) raster.getDataBuffer();
byte[] data = dataBuffer.getData();
frame.get(0, 0, data);
return image;
}
}

Java rotate image turns part of background black

When I try to rotate an image it appears that a part of the background turns black (my images are transparents)
Background white
Part of background turns black
Here's the code that rotate the image :
public BufferedImage rotate(int height, int width, BufferedImage originalImg, int angle) {
BufferedImage rotateImage = null;
try {
rotateImage = new BufferedImage(height, width, BufferedImage.TYPE_INT_RGB);
AffineTransform a90 = AffineTransform.getRotateInstance(Math.toRadians(angle), height / 2, width / 2);
AffineTransformOp op90 = new AffineTransformOp(a90, AffineTransformOp.TYPE_BILINEAR);
op90.filter(originalImg, rotateImage);
}
catch (Exception e) {
System.err.println(e);
}
return rotateImage;
}

So, I downloaded you "original" image (which is not square), modified it so it was square, run your code, got a java.awt.image.ImagingOpException: Unable to transform src image exception, changed BufferedImage.TYPE_INT_RGB to BufferedImage.TYPE_INT_ARGB and got...
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
try {
BufferedImage img = ImageIO.read(Main.class.getResource("/Block.jpg"));
BufferedImage rotate = rotate(img.getHeight(), img.getWidth(), img, 90);
JPanel panel = new JPanel();
panel.add(new JLabel(new ImageIcon(img)));
panel.add(new JLabel(new ImageIcon(rotate)));
JOptionPane.showMessageDialog(null, panel);
} catch (IOException ex) {
ex.printStackTrace();
}
}
public static BufferedImage rotate(int height, int width, BufferedImage originalImg, int angle) {
BufferedImage rotateImage = null;
try {
rotateImage = new BufferedImage(height, width, BufferedImage.TYPE_INT_ARGB);
AffineTransform a90 = AffineTransform.getRotateInstance(Math.toRadians(angle), height / 2, width / 2);
AffineTransformOp op90 = new AffineTransformOp(a90, AffineTransformOp.TYPE_BILINEAR);
op90.filter(originalImg, rotateImage);
} catch (Exception e) {
e.printStackTrace();
}
return rotateImage;
}
}
My, "gut" feeling is to also modify the rotate method, as it shouldn't need width and height values;
public static BufferedImage rotate(BufferedImage originalImg, int angle) {
BufferedImage rotateImage = null;
try {
rotateImage = new BufferedImage(originalImg.getWidth(), originalImg.getHeight(), BufferedImage.TYPE_INT_ARGB);
AffineTransform a90 = AffineTransform.getRotateInstance(Math.toRadians(angle), originalImg.getWidth() / 2, originalImg.getHeight() / 2);
AffineTransformOp op90 = new AffineTransformOp(a90, AffineTransformOp.TYPE_BILINEAR);
op90.filter(originalImg, rotateImage);
} catch (Exception e) {
e.printStackTrace();
}
return rotateImage;
}
it should be using the original image's dimensions directly. This is will highlight possible errors in your images. This also assumes that you only want to rotate the image by increments of 90 degrees

Manipulating a colored image in matrix form in java

I am working on a project related to colored image manipulation using JAVA.
I got to know the conversion of the colored image into a matrix using a getSample method of Raster class,
pixels[x][y]=raster.getSample(x,y,0);
I got the matrix in pixels[][] (only the values in red band).
Then i converted the matrix back to image using WritableRaster as,
raster.setSample(i,j,0,pixels[i][j]);
I converted it to image using,
*BufferedImage image=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
image.setData(raster);*
But the problem is,
1) I want the colored image to be displayed as it is whereas i am getting only a particular band(like only red, only blue . . ) because I have to specify a band as per the prototype of the method setSample and getenter code hereSample.
2) How can i get a 2d matrix representing a colored image(of all 3 bands represented in 3 different matrices)
Here is the code that i wrote with the help of snippets of code online...
import java.awt.Image;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.awt.image.SampleModel;
import java.awt.image.WritableRaster;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
class TestImage {
ImageIcon icon;
SampleModel sampleModel;
public static void main(String args[]){
TestImage mamu = new TestImage();
File file = new File("photo.jpg");
mamu.compute(file);
}
public void compute(File file){
try{
BufferedImage img= ImageIO.read(file);
Raster raster=img.getData();
sampleModel = raster.getSampleModel();
int w=raster.getWidth(),h=raster.getHeight();
int pixels[][]=new int[w][h];
for (int x=0;x<w;x++){
for(int y=0;y<h;y++){
pixels[x][y]=raster.getSample(x,y,0);
}
}
Image image = getImage(pixels);
JFrame frame = new JFrame("uff");
ImageIcon icon = new ImageIcon(image);
JLabel label = new JLabel(icon);
frame.setContentPane(label);
frame.setVisible(true);
frame.setSize(200,200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}catch (Exception e){
e.printStackTrace();
}
}
public java.awt.Image getImage(int pixels[][]){
int w=pixels.length;
int h=pixels[0].length;
WritableRaster raster= Raster.createWritableRaster(sampleModel, new Point(0,0));
for(int i=0;i<w;i++){
for(int j=0;j<h;j++){
raster.setSample(i,j,0,pixels[i][j]);
}
}
BufferedImage image=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
image.setData(raster);
File output=new File("check.jpg");
try {
ImageIO.write(image,"jpg",output);
}catch (Exception e){
e.printStackTrace();
}
return image;
}
}

You may be looking or java.awt.image.LookupOp, which uses a java.awt.image.LookupTable to modify bands en bloc. Several examples are cited here. The image below illustrates inversion:
short[] invert = new short[256];
for (int i = 0; i < 256; i++) {
invert[i] = (short) (255 - i);
}
BufferedImageOp invertOp = new LookupOp(new ShortLookupTable(0, invert), null));
invertOp.filter(src, dst);

How to draw on buffered image with java graphics?

My issue: Every time I create graphics from a buffered image and then draw another buffered image to the graphics I get an image that is blank.
My code is as follows.
Graphics2D g2d = atlas.createGraphics();
// images[i] is a buffered image read the fileio
g2d.drawImage(images[i], null, x, y); // Image is not blank, been tested
g2d.dispose();
// then save image
Ironically after trying to create a self contained example which is as follows... it worked. I am not quite sure what I am doing wrong in my code and I am wondering if it is because maybe an image is not static, could an image or another variable not being static affect my drawing?
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import javax.imageio.ImageIO;
public class Main {
public static void main(String[] args) {
String FOLDER_LOCATION = "./Images/";
BufferedImage atlas = new BufferedImage(2048, 2048, BufferedImage.TYPE_INT_ARGB);
BufferedImage redSquare = readImage(FOLDER_LOCATION + "red.png");
Graphics2D g2d = atlas.createGraphics();
g2d.drawImage(redSquare, null, 0, 0);
g2d.dispose();
writeImage(atlas, FOLDER_LOCATION + "atlas.png");
}
public static BufferedImage readImage(String location) {
BufferedImage img = null;
InputStream is = null;
try {
is = new FileInputStream(location);
img = ImageIO.read(is);
} catch(Exception e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch(Exception e) {
e.printStackTrace();
}
}
return img;
}
public static void writeImage(BufferedImage bi, String location) {
try {
File file = new File(location);
ImageIO.write(bi, "png", file);
} catch(Exception e) {
e.printStackTrace();
}
}
}
After I save the image I see just a blank 2048 by 2048 image. I printed the entire image out and I get (0, 0, 0), but if I print out any of the image I am drawing to the atlas I get something like (72, 32, 283).
I am not quite sure what I am doing wrong, but my entire source code for this project is here: https://github.com/gemurdock/jTextureAtlas and the branch I am working on is here: https://github.com/gemurdock/jTextureAtlas/tree/alpha.
You have to look at the alpha branch to see my code