MImage.java

/*******************************************************
 CS4551 Multimedia Software Systems
 @ Author: Elaine Kang

MImage class is for a 24bit RGB image only.
MImage is a platform independent class definition and stores image data into a byte array.
MImage provides utility functions such as reading data from and writing data to a PPM file.
 *******************************************************/

import java.io.*;
import java.util.*;

public class MImage
{
  private String fileName;		// Input file name
  private int pixelDepth=3;		// pixel depth in bye
  private byte data[];			// raw data in byte array -- char is 16bits in Java
  private int width;
  private int height;

  public MImage(int w, int h)
  // create an empty image with w(idth) and h(eight)
  {
	fileName = "";
	width = w;
	height = h;
	data = new byte[w*h*pixelDepth];
	System.out.println("Created an empty image with size " + w + "x" + h);
  }

  public MImage(String fn)
  // Create an image and read the data from the file
  {
	  fileName = fn;
	  readPPM(fileName);
	  System.out.println("Created an image from " + fileName+ " with size "+getW()+"x"+getH());
  }

  public int getW()
  {
	return width;
  }

  public int getH()
  {
	return height;
  }

  public int getSize()
  // return the image size in byte
  {
	return getW()*getH()*pixelDepth;
  }
  
  public String getName()
  // return the image name
  {
	return fileName;
  }
  
  // (0,0) is the upper left corner of the image
  // (w-1,0) is the upper right corner of the image
  // (0, h-1) is the lower right corner of the image
  // (w-1, h-1) is the lower right corner of the image
    
  public void getPixel(int x, int y, byte[] rgb)
  // retreive rgb values at (x,y) through rgb[] byte array
  {
	  if (x >=0 && x < width && y >=0 && y < height) {
		  rgb[0] = data[y*width*pixelDepth+x*pixelDepth];
		  rgb[1] = data[y*width*pixelDepth+x*pixelDepth+1];
		  rgb[2] = data[y*width*pixelDepth+x*pixelDepth+2];
	  }
   }


  public void getPixel(int x, int y, int[] rgb)
  // retreive rgb values at (x,y) through rgb[] int array
  {
	  if (x >=0 && x < width && y >=0 && y < height) {
		byte r = data[y*width*pixelDepth+x*pixelDepth];
		byte g = data[y*width*pixelDepth+x*pixelDepth+1];
		byte b = data[y*width*pixelDepth+x*pixelDepth+2];
		
		// converts singed byte value (~128-127) to unsigned byte value (0~255)
		rgb[0]= (int) (0xFF & r);
		rgb[1]= (int) (0xFF & g);
		rgb[2]= (int) (0xFF & b);
	  }
  }


  public void setPixel(int x, int y, byte[] rgb)
  // set byte rgb values at (x,y)
  {
	  if (x >=0 && x < width && y >=0 && y < height) {
		data[y*width*pixelDepth+x*pixelDepth] = rgb[0];
		data[y*width*pixelDepth+x*pixelDepth+1] = rgb[1];
		data[y*width*pixelDepth+x*pixelDepth+2] = rgb[2];
	  }
  }

  public void setPixel(int x, int y, int[] irgb)
  // set int rgb values at (x,y)
  {
	  if (x >=0 && x < width && y >=0 && y < height) {
		data[y*width*pixelDepth+x*pixelDepth] = (byte) irgb[0];
		data[y*width*pixelDepth+x*pixelDepth+1] = (byte) irgb[1];
		data[y*width*pixelDepth+x*pixelDepth+2] = (byte) irgb[2];
	  }
  }

  public void printPixel(int x, int y)
  // Print rgb pixel in unsigned (0~255)
  {
	  if (x >=0 && x < width && y >=0 && y < height) {
		byte r = data[y*width*pixelDepth+x*pixelDepth];
		byte g = data[y*width*pixelDepth+x*pixelDepth+1];
		byte b = data[y*width*pixelDepth+x*pixelDepth+2];
		
		System.out.println("RGB Pixel value at ("+x+","+y+"): ("+(0xFF & r)+","+(0xFF & g)+","+(0xFF & b)+")");
	  }
   }

  public void readPPM(String fileName)
  // read data from a PPM file
  {
	File fIn = null;
	FileInputStream fis = null;
	BufferedReader in = null;
	DataInputStream din = null;


	try{
		fIn = new File(fileName);
		in = new BufferedReader(new FileReader(fIn));
		din = new DataInputStream(new FileInputStream(fIn));
		int headerLength=0;

		System.out.println("Reading "+fileName+"...");

		// read Identifier
		String header = in.readLine();
		if(!header.equals("P6"))
		{
			System.err.println("This is NOT P6 PPM. Wrong Format.");
			System.exit(0);
		}
		
		headerLength += header.getBytes().length;

		// read Comment line
		header = in.readLine();
		headerLength += header.getBytes().length;

		// read width & height
		header = in.readLine();
		headerLength += header.getBytes().length;
		String[] WidthHeight = header.split(" ");
		width = Integer.parseInt(WidthHeight[0]);
		height = Integer.parseInt(WidthHeight[1]);

		// read maximum value
		header = in.readLine();
		headerLength += header.getBytes().length;
		int maxVal = Integer.parseInt(header);

		if(maxVal != 255)
		{
			System.err.println("Max val is not 255");
			System.exit(0);
		}

		// read pixel data and store it into data array
		data = new byte[width*height*pixelDepth];
		din.skipBytes(headerLength+4);
		din.read(data);
		
		din.close();
		in.close();

		System.out.println("Read "+fileName+" Successfully.");

	} // try
	catch(Exception e)
	{
		System.err.println(e.getMessage());
	}
  }

  public void write2PPM(String fileName)
  // write the image data into a PPM file
  {
	FileOutputStream fos = null;
	PrintWriter dos = null;

	try{
		fos = new FileOutputStream(fileName);
		dos = new PrintWriter(fos);

		System.out.println("Writing the Image buffer into "+fileName+"...");

		// write header
		dos.print("P6"+"\n");
		dos.print("#CS451"+"\n");
		dos.print(getW() + " "+ getH() +"\n");
		dos.print(255+"\n");
		dos.flush();

		// write data
		fos.write(data);
		fos.flush();

		dos.close();
		fos.close();

		System.out.println("Wrote into "+fileName+" Successfully.");

	} // try
	catch(Exception e)
	{
		System.err.println(e.getMessage());
	}
  }
  
  public String toString() 
  { 
        return getName()+ " : " + getW() + " X " + getH() + " : " + getSize() + " bytes"; 
  } 
} // MImage class