store your image to a variable like below
mArrImgData = new byte[16800];
grayFrame.Copy(FaceRect).Resize(120, 140, INTER.CV_INTER_LINEAR).Bytes.CopyTo(mArrImgData, 0);
and then insert to database directly:
msQueryString = "INSERT INTO VGPSystem(Valid_From,Today_date,Validity,VGP_Name,VGP_Company,VGP_VehicleNo,VGP_PHNO,Issuer_Name,Issuer_Department,Pass_Number,Sl_No,VPhoto) values ("
+"'" + dtpValidFrom.Value.ToString("MM/dd/yyyy")+ "',"
+ "'" + System.DateTime.Now.ToString("MM/dd/yyyy")
+"'," + cmbValidity.Text
+ ",'" + txtVisitorName.Text
+ "','" + txtVisitorComAddr.Text
+ "','" + txtVisitorVehicleNum.Text
+ "','" + txtVisitorPersonalNum.Text
+ "','" + txtIssuername.Text
+ "','" + txtIssuerDept.Text
+ "','" + txtPnum.Text
+ "','" + lTemp
+ "'," + "@Imagedata" + ")";
objcmd.Parameters.Add("@Imagedata", SqlDbType.Image, mArrImgData.Length).Value = mArrImgData;
Best Of Luck for your Project!