how to get pixel value of each pixel of a gray-scale or black-white image?

[ashish donvir]

can any one suggest me the method to get actual pixel value of each pixel of a gray scale image?

i used this code to get pixel. But it just gives me red value of an pixel? I don't know that black-white or Gray Scale image contains RGB pixels or not, So please tell me that, the method i used is right or wrong? And also when i plotted histogram for my image it was exactly opposite to the imajeJ histogram for same image. So i guess my method to grab pixel of Gray Scale image is somewhere wrong

So If it is wrong what is the right way to get pixel.
here is my code

 PlanarImage image = JAI.create("fileload", "C:\\16bit images\\alpXray.tiff");
 BufferedImage bi = image.getAsBufferedImage();
  int[] bins = new int[256];
 int b=0;
for (int x = 0; x < bi.getWidth(); x++) {
   
         for (int y = 0; y < bi.getHeight(); y++) {

             int p= bi.getRaster().getSample(x, y,b);    //   (1)  b=0 for red   (2)b=1 for green  (3) b=2 for bule
          
           p=p/256;
  
           bins[p]++;  
       }

 }

[Maneesh Godbole]

http://www.coderanch.com/t/258773/Applets/java/getting-color-particular-pixel-image#1201744