huffman coding in java, something wrong for pictures

public class HopeHuffMan {

  
    public static void main(String[] args) throws IOException {
        
        
       FileInputStream input = new FileInputStream( "f:/testpic.bmp");
         
        
        String text=Change_input_to_string_Text(input);
        
             
   int[] counts = getCharacterFrequency(text); // Count frequency
     
   
    Tree tree = getHuffmanTree(counts); // Create a Huffman tree
      String[] codes = getCode(tree.root); // Get codes

                        
                          int k1=text.length();
                          Compress(text,codes);
                         Decompress (k1,tree);
                  
    }
    
       


    
     private static String Change_input_to_string_Text(FileInputStream input1) throws IOException{                
                   int ch;
                StringBuilder strContent = new StringBuilder("");
                                 
                 while((ch = input1.read()) != -1)
                  strContent.append((char) ch);
                 input1.close();
                String text = strContent.toString();
               
              
               
     return text;      
    }
    
 
    private static int[] getCharacterFrequency(String text) {
        int[] counts = new int[256]; // 256 ASCII characters
    
    for (int i = 0; i < text.length(); i++)
      counts[(int)text.charAt(i)]++; // Count the character in text
    
    return counts;
    }
    
    
    
      private static Tree getHuffmanTree(int[] counts) {
        // Create a heap to hold trees
    Heap<Tree> heap = new Heap<Tree>(); // Defined in Listing 24.10
    for (int i = 0; i < counts.length; i++) {
      if (counts[i] > 0)
        heap.add(new Tree(counts[i], (char)i)); // A leaf node tree
    }
    
    while (heap.getSize() > 1) { 
      Tree t1 = heap.remove(); // Remove the smallest weight tree
      Tree t2 = heap.remove(); // Remove the next smallest weight 
      heap.add(new Tree(t1, t2)); // Combine two trees
    }

    return heap.remove(); // The final tree
    }
    
        private static String[] getCode(Node root) {
         if (root == null) return null;    
    String[] codes = new String[2 * 128];
    assignCode(root, codes);
    return codes;
    }

    
   
    
    private static void assignCode(Node root, String[] codes) {
        if (root.left != null) {
      root.left.code = root.code + "0";
      assignCode(root.left, codes);
      
      root.right.code = root.code + "1";
      assignCode(root.right, codes);
    }
    else {
      codes[(int)root.element] = root.code;
    }
    }
  

       
    
    private static int Compress (String text,String[] codes){
                           String s="";
                        char cd = 0;
                     for(int i=0;i<text.length();++i){
                         cd=text.charAt(i);
                         s=s+codes[cd];
                     }
                     byte [] bytes;
                     bytes=s.getBytes();
                        for(int i=0;i<bytes.length;++i){
                         if(bytes[i]==48) bytes[i]=0;
                         if(bytes[i]==49) bytes[i]=1;
                     }
                      
                     BitOutputStream fop2 = new BitOutputStream("f:/is.oli");
                       for (int i = 0; i < bytes.length; i++) {
                       fop2.writeBit(bytes[i]);
            }
               fop2.close();
               return bytes.length;  
    }
           
    
    

    
    private static void Decompress (int b,Tree t) throws FileNotFoundException, IOException{
        
        BufferedWriter out = new BufferedWriter(new FileWriter("f:/unziped.txt"));
                   
                 BitInputStream fop2 = new BitInputStream("f:/is.oli");
                 System.out.print("\n");
               for (int i = 0;i<b ; i++) {
                        Node x = t.root;
                    while (!x.isLeaf()) {
                    int bit=fop2.readBit();
                  if (bit==1) x = x.right;
                  if (bit==0) x = x.left; 
                }
                       out.write(x.element);
                     
                      
                       }
                 System.out.print("\n");
                   out.close();      
                   fop2.close();
                                  
    }
       
    
    
}