Use this type of code .. Defiantly you will solve your Problem
ReportViewer1.LocalReport.EnableExternalImages = true;
string imagePath = new Uri(Server.MapPath(ds.Tables[0].Rows[0]["sImg"].ToString())).AbsoluteUri;
ReportParameter rp1 = new ReportParameter("img", imagePath);
string imagePath1 = new Uri(Server.MapPath(ds.Tables[0].Rows[0]["pimg"].ToString())).AbsoluteUri;
ReportParameter rp2 = new ReportParameter("priImg", imagePath1);
string imagePath3 = new Uri(Server.MapPath(ds.Tables[0].Rows[0]["sign"].ToString())).AbsoluteUri;
ReportParameter rp3 = new ReportParameter("presiImg", imagePath3);
string imagePath4 = new Uri(Server.MapPath(ds.Tables[0].Rows[0]["signsecretary"].ToString())).AbsoluteUri;
ReportParameter rp4 = new ReportParameter("secImg", imagePath4);
ReportViewer1.LocalReport.SetParameters(new ReportParameter[] { rp1, rp2,rp3,rp4 });
Note: Here ds is DataSet Class object Which have the image physical path.
Thanks
AARIF SHAIKH