Q:

how to calculate pixel count of three images at same time

How can i calculate total pixel of three images at the same time?
I was tried with java Swing Worker and Thread, i got the answer but it takes 1.30 min to return total pixel count(30 seconds for each image, image size 480*303) of specified range. But I need to get answers of three images at same time within 30 sec.
public class ImageProcessor1 implements Runnable{
static int blackPix=0;
BufferedImage tempImg;
public static int blackPixel=0;
public ImageProcessor1(String path) throws Exception{
tempImg = ImageIO.read(new File(path));
}

private static int[] getPixelData(BufferedImage img, int x, int y) {
    int argb = img.getRGB(x, y);

    int rgb[] = new int[]{
        (argb >> 16) & 0xff, //red
        (argb >> 8) & 0xff, //green
        (argb) & 0xff //blue
    };
    System.out.println("Process1 :rgb: " + rgb[0] + " " + rgb[1] + " " + rgb[2]);
    return rgb;
}

@Override
public void run() {
     int[][] pixelData = new int[tempImg.getHeight() * tempImg.getWidth()][3];
        int[] rgb;
        int height=tempImg.getHeight();
        int width=tempImg.getWidth();
        int counter = 0;
        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                rgb = getPixelData(tempImg, i, j);
                if(rgb[0]<125 && rgb[0]>105 && rgb[1]<125 && rgb[1]>105 && rgb[2]<125 && rgb[2]>105)
                {
                    blackPixel+=1;
                }
            }
        }
}

}

A:

It is very strange that iterating over such a small picture takes you 30 seconds!
After a little profiling it seems, that having a println-statement in a hot loop is slowing you down dramatically.
After little modification of your code , a 10500x5788 image takes ~3secs on my machine.
The modified version:
package application;

import java.awt.image.BufferedImage;
import java.io.File;
import java.util.concurrent.TimeUnit;

import javax.imageio.ImageIO;

public class ImageProcessor1 implements Runnable {

  BufferedImage tempImg;
  public static int blackPixel = 0;

  public ImageProcessor1(final String path) throws Exception {
    final long start = System.nanoTime();

    tempImg = ImageIO.read(new File(path));
    // Use tracing, profiling and sampling to proof performance issues and fixes
    System.out.println("ImageIO took " + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start)
        + " ms.");
  }

  @Override
  public void run() {
    long start = System.nanoTime();
    final int height = tempImg.getHeight();
    System.out.println("Getting height '" + height + "' took "
        + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start) + " ms.");

    start = System.nanoTime();
    final int width = tempImg.getWidth();
    System.out.println("Getting width '" + width + "' took "
        + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start) + " ms.");

    start = System.nanoTime();

    // reuse variables
    int argb;
    int red;
    int green;
    int blue;

    for (int i = 0; i < width; i++) {
      for (int j = 0; j < height; j++) {
        // HOT LOOP. Do as little as possible. No println calls!
        argb = tempImg.getRGB(i, j);

        // inline all method calls
        red = argb >> 16 & 0xff; // red
        green = argb >> 8 & 0xff; // green
        blue = argb & 0xff; // blue

        if (red < 125 && red > 105 && green < 125 && green > 105 && blue < 125 && blue > 105) {
          blackPixel += 1;
        }
      }
    }
    System.out.println("Iterating pixels took "
        + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start) + " ms.");
  }

  public static void main(final String[] args) throws Exception {
    new ImageProcessor1("big.jpg").run();
    System.out.println("Number of blackpixels = " + blackPixel);
  }

}

On a more general note, you have to be careful with your approach, because you read all of the image into RAM, and then process it. If you do that with 3 or more large images at once, there is a chance of an OutOfMemoryError. If that becomes an issue, you could read an image in as an input stream and process only small buffers of the image at a time.
To see how this can be done see http://imagej.nih.gov/ij/source/ij/io/ImageReader.java .
To see how to accumulate the output of multiple threads , see How write mulithreaded code and accumulate the output from all the threads in a single file .

