System.Security.SecurityException when trying to access an image

Hi All,

 I have made an DataTable with custom columns it. One of the column is for image
 resTable.Columns.Add("ProducImage",typeof(byte []));
 
I am trying to add the image using the following statements
 System.Drawing.Bitmap objBmp;
 string strImg = "./FullPhotos/" + TblProducts.Rows[i]["Category"] + "_" + TblProducts.Rows[i]["SubCategory"] + ".jpg";

objBmp = new System.Drawing.Bitmap(strImg);
The problem is that  an exception is occuring when the execution reach
objBmp = new System.Drawing.Bitmap(strImg); 
The exception message is as follows
Description: The
application attempted to perform an operation not allowed by the
security policy.  To grant this application the required permission ...