Source Code : Reading a pgm file in Java

  Reading a pgm file in Java

I need to read a pgm file and store the array of values contained in it in a 2D array. In PGM format, each pixel is specified by a gray value between 0 and MaxVal. The first three lines give information related to the image: magic number, height, width and maxVal. The file also includes whitespaces. Lines starting with # are comments. This is what I had written till now.

publicclass PGM{publicstaticvoid main(String args[])throwsException{FileInputStream f =newFileInputStream("C:\\......\\brain_001.pgm");DataInputStream d =newDataInputStream(f);
  d.readLine();//first line contains P5String line = d.readLine();//second line contains height and widthScanner s =newScanner(line);int width = s.nextInt();int height = s.nextInt();
  line = d.readLine();//third line contains maxVal
  s =newScanner(line);int maxVal = s.nextInt();byte[][] im =newbyte[height][width];for(int i =0; i <258; i++){for(int j =0; j <258; j++){
  im[i][j]=-1;}}int count =0;byte b;try{while(true){
  b =(byte)(d.readUnsignedByte());if(b =='\n'){//do nothing if new line encountered}elseif(b =='#'){
  d.readLine();}elseif(Character.isWhitespace(b)){// do nothing if whitespace encountered}else{
  im[count / width][count % width]= b;
  count++;}}}catch(EOFException e){}System.out.println("Height="+ height);System.out.println("Width="+ height);System.out.println("Required elemnts="+(height * width));System.out.println("Obtained elemnets="+ count);}}

When the program is run, I get the following output:

Height=258Width=258Required elemnts=66564Obtained elemnets=43513

The number of elements (each corresponding to a gray value) are less than the required ones. When I open the file with a PGM viewer, everything shows up correctly. Also, when I print the contents of the array, I see a lot of negative values. But all of them have to be greater than or equal to zero. Where have I gone wrong?

Updated to handle P2 and P5 flavors of PGM)

publicstaticvoid main(String args[])throwsException{try{InputStream f =ClassLoader.getSystemClassLoader().getResourceAsStream("lena.pgm");BufferedReader d =newBufferedReader(newInputStreamReader(f));String magic = d.readLine();// first line contains P2 or P5String line = d.readLine();// second line contains height and widthwhile(line.startsWith("#")){
  line = d.readLine();}Scanner s =newScanner(line);int width = s.nextInt();int height = s.nextInt();
  line = d.readLine();// third line contains maxVal
  s =newScanner(line);int maxVal = s.nextInt();byte[][] im =newbyte[height][width];int count =0;int b =0;try{while(count < height*width){
  b = d.read();if( b <0)break;if(b =='\n'){// do nothing if new line encountered}//  else if (b == '#') {//  d.readLine();//  } //  else if (Character.isWhitespace(b)) { // do nothing if whitespace encountered//  } else{if("P5".equals(magic)){// Binary format
  im[count / width][count % width]=(byte)((b >>8)&0xFF);
  count++;