plsz i want the coding details of line

package vc.api;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.Random;
import javax.imageio.ImageIO;
import vc.controller.Controller;

/**
 *
 1. @author ????
 */
public class VCAPI {
    private static BufferedImage pic1;
    private static BufferedImage pic2;
    private static BufferedImage out;

  static int getBrightness(int rgb) {
    int r,g,b;
    Color pixColour = new Color(rgb);
    r=pixColour.getRed();
    g=pixColour.getGreen();
    b=pixColour.getBlue();
    rgb = (int)((r+g+b)/3);
    return rgb;
  }
//------------------------------------------------------------------------------
  static BufferedImage monochrome(BufferedImage picture) {
    int i,j,min=128,max=128,value=0,col;

    for (i=0;i<picture.getHeight();i++){
      for (j=0;j<picture.getWidth();j++) {
        value=getBrightness(picture.getRGB(j,i));
        if (value<min) min=value;
        if (value>max) max=value;
      }
    }

    value=(int)Math.ceil((max+min)/2);

    for (i=0;i<picture.getHeight();i++){
      for (j=0;j<picture.getWidth();j++) {
        col=getBrightness(picture.getRGB(j,i));
        if (col<value) picture.setRGB(j,i,-16777216);//black
        else picture.setRGB(j,i,-1);//white
      }
    }

    return picture;
  }
//------------------------------------------------------------------------------
  static BufferedImage meldImages(BufferedImage template, BufferedImage random) {
    int i,j;
    BufferedImage output = new BufferedImage(template.getWidth(),template.getHeight(),BufferedImage.TYPE_INT_RGB);

    for (i=0;i<template.getHeight();i++){
      for (j = 0; j < template.getWidth(); j++) {


 2. **if (template.getRGB(j,i)<-8388608) {//black if
    (random.getRGB(j,i)<-8388608)
    output.setRGB(j,i,-1); else
    output.setRGB(j,i,-16777216);**

========================================

        }
        else {
          if (random.getRGB(j,i)<-8388608) output.setRGB(j,i,-16777216);
          else output.setRGB(j,i,-1);
        }
      }
    }
    return output;
  }
//------------------------------------------------------------------------------
  static BufferedImage makeGrey(BufferedImage template) {//note; 0 is black in the top left corner, 1 has white in that corner
    BufferedImage output = new BufferedImage(template.getWidth()*2,template.getHeight()*2,BufferedImage.TYPE_INT_RGB);
    int i,j;

    for (i=0;i<template.getHeight();i++){
      for (j=0;j<template.getWidth();j++) {
        if (template.getRGB(j,i)<-8388608) {//black
          output.setRGB((j*2),(i*2),-16777216);//black
          output.setRGB((j*2),(i*2)+1,-1);//white
          output.setRGB((j*2)+1,(i*2),-1);//white
          output.setRGB((j*2)+1,(i*2)+1,-16777216);//black
        }
        else {
          output.setRGB((j*2),(i*2),-1);//white
          output.setRGB((j*2),(i*2)+1,-16777216);//black
          output.setRGB((j*2)+1,(i*2),-16777216);//black
          output.setRGB((j*2)+1,(i*2)+1,-1);//white
        }

      }
    }
    return output;
  }

in the above code i want details about the valule...in meldimage() function ....we can see the for loop...

that is

if (template.getRGB(j,i)<-8388608) {//black if
    (random.getRGB(j,i)<-8388608)
    output.setRGB(j,i,-1); else
    output.setRGB(j,i,-16777216);

getRGB(j,i)<-8388608

why can put this value?
its default value ?
or if its any value of rgb

second setRGB(j,i,-16777216) y can use this value...its constant one

how 2 get this value...
plsz explain this code....its come visual cryptography grayconversion coding 

plsz anybody helpme..for this code

what is use of this value?
why can check < -8388608?
how to got this value -8388608
plsz helpme

i want this coding details plsz friends helpme..