reading pixel values from images

[utkarsh 1]

hi im doing project on extracting a character from images. for that purpose i want to read pixel values from images and store in the 1d array and this array im using for testing purpose. and in using only grayscale images. can anyone provide me the java code to read pixel vlues from images and store it in array.

[Norm]

Look at the BufferedImage getRGB() method.

[DarrylBurke]

can anyone provide me the java code

No, this is a forum, not a code mill. If you want someone to write your programs for you, hire a programmer.

db

[utkarsh 1]

i have written code to read pixel values from images

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.JFrame;

public class ShowImage extends Panel {
BufferedImage image;

public ShowImage() {
try {
System.out.println("Enter image name\n");
BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
String imageName=bf.readLine();
File input = new File("ab.jpg");
image = ImageIO.read(input);
} catch (IOException ie) {
System.out.println("Error:"+ie.getMessage());
}

}

public void paint(Graphics g) {
g.drawImage( image, 100,100, null);
}

static public void main(String args[]) throws Exception {
JFrame frame = new JFrame("image");
Panel panel = new ShowImage();
frame.getContentPane().add(panel);
frame.setSize(500, 500);
frame.setVisible(true);
}
}


im not geting any error but geting negative values can u tel me the solution for this

[Norm]

geting negative values

Please show the values you are getting.
What statement generates the negative values?

[utkarsh 1]

im extremally sorry i posted wrong code

this is the correct code

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import java.lang.Exception;

import java.awt.Graphics;
import java.awt.image.PixelGrabber;
import java.awt.image.*;
import java.util.*;


  public class ShowImage3 extends Panel {
      BufferedImage  image;
    public ShowImage3() {
      try{
      System.out.println("Enter image name\n");
      BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
       String imageName=bf.readLine();
      File input = new File("ab.jpg");
          image = ImageIO.read(input);

 int w = image.getWidth(null);
int h = image.getHeight(null);


int pixels[] = new int[w*h];
      PixelGrabber pg = new PixelGrabber(image,0,0,w,h,pixels,0,w);
  
pg.grabPixels();

int[] data = (int[]) pg.getPixels();
      


for(int i=0;i<w*h;i++)
{
System.out.println(""+data[i]);
}
 




      }
    
 catch (Exception ie) {
        System.out.println("Error:"+ie.getMessage());
      }  
}

    public void paint(Graphics g) {
      g.drawImage( image, 100,100, null);
    }
  
    static public void main(String args[]) throws Exception {
      JFrame frame = new JFrame("image");
      Panel panel = new ShowImage3();
      frame.getContentPane().add(panel);
      frame.setSize(500, 500);
      frame.setVisible(true);
    }
  }

and output which im geting is


-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1

[Norm]

What color do those values represent?
You should look at the values in hexadecimal not in base 10.
-1 is xFFFFFFFF

[utkarsh 1]

color of pixel value is black

[Norm]

What values do you expect to print out for black?

[utkarsh 1]

1 if black pixel is present else print zero

[Norm]

1 if black pixel is present else print zero

Why do you expect the RGB value for a black pixel to be 1?
There are 24 bits in the RGB value.
Print out the bits for the Color.black object to see the value of the bits are for black.

[utkarsh 1]

which part of code i should modify to get proper output

[Norm]

What output is "proper" output?
The code works for me.

[utkarsh 1]

what output ur geting same -1 ya something else

[Norm]

The output will depend on the color of the image. You would get -1 for white.

I get this (in hexadecimal) for a solid colored image: ffff9966 ffff9966 ffff9966 ffff9966 ffff9966 ....
If you want to see the color(sort of orange), use the Color class's constructor to create this color.

[utkarsh 1]

if im using only grayscale images means it contains only black pixel
what should be the output
what does -1 value represnt

[Norm]

-1 is 0xFFFFFFFF
You can use the Color class's constructor to create a color object and display it to see what color it is.
For example: new Color(0xFF, 0X15, 0xFF)
The Integer toHexString() method is useful for printing out the RGB values in a more understandable form.

[utkarsh 1]

thanks a lot for ur help

[camickr]

Don't use AWT components in a Swing application. Swing component start with "J".