System.Text.UTF8Encoding UTF8Encoding = 
new System.Text.UTF8Encoding();
result = UTF8Encoding.GetBytes("ü");

 
System.IO.FileInfo fi = new System.IO.FileInfo (Application.StartupPath 
+ "\\test.jpg");
 
FileStream stream = fi.Open (System.IO.FileMode.OpenOrCreate,
System.IO.FileAccess.ReadWrite);
 
 
BinaryReader br = new BinaryReader(stream,Encoding.UTF8);
int buffer = 200000;
byte[] BytesReadFromFile = new byte[buffer]; 
br.Read(BytesReadFromFile, 0, buffer);