A:  The TGraphicField descends from TBlobField which has a LoadFromFile() method.

unit Blobs;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, DB, DBTables, Menus, StdCtrls, DBCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    DBNavigator1: TDBNavigator;
    DBImage1: TDBImage;
    DataSource1: TDataSource;
    Table1: TTable;
    Button1: TButton;
    OpenDialog1: TOpenDialog;
    Table1TheBlob: TGraphicField; {from a custom PW table}
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
  if OpenDialog1.execute then begin
    table1.edit;
    Table1TheBlob.LoadFromFile(OpenDialog1.FileName);
    table1.post;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  OpenDialog1.InitialDir := 'c:\windows';
end;

end.