android photography

import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.util.Scanner;

public class CharEraser {

 public static void main(String[] args) throws IOException {

  String inputfile = "input.txt";
  String outputfile = "output.txt";
  int number_of_char_to_erased = 3;

  String line = "";

  File input = new File(inputfile);
  Scanner scan = new Scanner(input);
  File output = new File(outputfile);
  PrintStream print = new PrintStream(output);

  while (scan.hasNext()) {
   line = scan.nextLine();
   line = line.substring(number_of_char_to_erased);
   print.println(line);
  }

  scan.close();
  print.close();
 }
}

There are many libraries which are used to Image processing applications. But the algorithms behind these libraries use basic mathematical operation. I hope to bring you series of blog posts which describe the fundamental image processing algorithms implemented in mathematical operation without using any library. Following java class change the brightness of an image.
We should input our image to the method changeBrightness as a BufferedImage. increasingFactor is an integer which determine the brightness level of the image. Positive values will increase the brightness while negative values decrees. Range of the increasingFactor should be between -255 to 255.

Original Image

Brightness Increased

Brightness Decreased

package lakj.comspace.imageprocessor;

import java.awt.Color;
import java.awt.image.BufferedImage;

/**
 *Brightness Changing Class
 *by
 *Lak J Comspace
 * 
 */
public class Brightness {

    public BufferedImage changeBrightness(BufferedImage inImage, int increasingFactor) {

        //size of input image
        int w = inImage.getWidth();
        int h = inImage.getHeight();

        BufferedImage outImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);

        //Pixel by pixel navigation loop
        for (int i = 0; i < w; i++) {
            for (int j = 0; j < h; j++) {


                //get the RGB component of input imge pixel
                Color color = new Color(inImage.getRGB(i, j));

                int r, g, b;

                //change the value of each component
                r = color.getRed() + increasingFactor;
                g = color.getGreen() + increasingFactor;
                b = color.getBlue() + increasingFactor;


                //r,g,b values which are out of the range 0 to 255 should set to 0 or 255
                if (r >= 256) {
                    r = 255;
                } else if (r < 0) {
                    r = 0;
                }

                if (g >= 256) {
                    g = 255;
                } else if (g < 0) {
                    g = 0;
                }

                if (b >= 256) {
                    b = 255;
                } else if (b < 0) {
                    b = 0;
                }

                //set output image pixel component
                outImage.setRGB(i, j, new Color(r, g, b).getRGB());

            }
        }

        return outImage;
    }
}

This application is a simple client-server application which has a Android mobile client and a Java server which is run on a machine. In this example, client is run on the Android emulator and the server is run on the local host. In Android 10.0.2.2 is the IP address for local host. This application allow to type a text message on a text field and when the Send button is press the message is sent to the server. Server continuously listen to the port. When there is a incoming message server read it and show it on the standard output.

Client Side Application


SlimpleClientActivity.java

/*
 * This is a simple Android mobile client
 * This application read any string messege typed on the text field and 
 * send it to the server when the Send button is pressed
 * Author by Lak J Comspace
 */

package lakj.comspace.simpleclient;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class SimpleClientActivity extends Activity {

 private Socket client;
 private PrintWriter printwriter;
 private EditText textField;
 private Button button;
 private String messsage;

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  textField = (EditText) findViewById(R.id.editText1); //reference to the text field
  button = (Button) findViewById(R.id.button1);   //reference to the send button

  //Button press event listener
  button.setOnClickListener(new View.OnClickListener() {

   public void onClick(View v) {

    messsage = textField.getText().toString(); //get the text message on the text field
    textField.setText("");      //Reset the text field to blank

    try {

     client = new Socket("10.0.2.2", 4444);  //connect to server
     printwriter = new PrintWriter(client.getOutputStream(),true);
     printwriter.write(messsage);  //write the message to output stream

     printwriter.flush();
     printwriter.close();
     client.close();   //closing the connection

    } catch (UnknownHostException e) {
     e.printStackTrace();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  });

 }
}

/*
 * This is a simple server application
 * This server receive a string message from the Android mobile phone
 * and show it on the console.
 * Author by Lak J Comspace
 */
package simpleserver;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {

    private static ServerSocket serverSocket;
    private static Socket clientSocket;
    private static InputStreamReader inputStreamReader;
    private static BufferedReader bufferedReader;
    private static String message;

    public static void main(String[] args) {

        try {
            serverSocket = new ServerSocket(4444);  //Server socket

        } catch (IOException e) {
            System.out.println("Could not listen on port: 4444");
        }

        System.out.println("Server started. Listening to the port 4444");

        while (true) {
            try {

                clientSocket = serverSocket.accept();   //accept the client connection
                inputStreamReader = new InputStreamReader(clientSocket.getInputStream());
                bufferedReader = new BufferedReader(inputStreamReader); //get the client message
                message = bufferedReader.readLine();

                System.out.println(message);
                inputStreamReader.close();
                clientSocket.close();

            } catch (IOException ex) {
                System.out.println("Problem in message reading");
            }
        }

    }
}

//Converting Roman number to Arabic number
public static int convertRomToInt(String romanNum) {

 int result = 0;
 int mediator = 0;

 int length = romanNum.length();  //get number string length

  
 for (int i = 0; i < length - 1; i++) {     //this loop will add each Roman character value

  if (getInt(romanNum.charAt(i)) > getInt(romanNum.charAt(i + 1))) {

   result = result + getInt(romanNum.charAt(i)) + mediator;
   mediator = 0;

  } else if (getInt(romanNum.charAt(i)) == getInt(romanNum.charAt(i + 1))) {

   mediator = mediator + getInt(romanNum.charAt(i));

  } else if (getInt(romanNum.charAt(i)) < getInt(romanNum.charAt(i + 1))) {

   mediator = -mediator - getInt(romanNum.charAt(i));

  }

 }

 result = result + mediator + getInt(romanNum.charAt(length - 1));

 return result;

}

//Get integer value for corresponding Roman character
public static int getInt(char romanChar) {

 if (romanChar == 'I')
  return 1;
 else if (romanChar == 'V') {
  return 5;
 } else if (romanChar == 'X') {
  return 10;
 } else if (romanChar == 'L') {
  return 50;
 } else if (romanChar == 'C') {
  return 100;
 } else if (romanChar == 'D') {
  return 500;
 } else if (romanChar == 'M') {
  return 1000;
 }
 return (Integer) null;
}