Converting Doc file to jpg file or any image file

i've used this code...
Microsoft.Office.Interop.Word.Application wordApp = new Microsoft.Office.Interop.Word.Application();
Microsoft.Office.Interop.Word.Document wordDoc = new Microsoft.Office.Interop.Word.Document();

object falseVal = false;


string fileName = @"D:\document.doc";
FLimage.PostedFile.SaveAs(Server.MapPath("~/temp") + "/test.docx");

System.IO.MemoryStream ms = new System.IO.MemoryStream(System.IO.File.ReadAllBytes(Server.MapPath("~/temp") + "/test.docx"));
System.Drawing.Image img = System.Drawing.Image.FromStream(ms);
img.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);


but got an error "parameter is not valid" on the line
....Image.FromStream(ms);