var
  MyBitmap: TBitmap;
  MyRect: TRect;
..

MyBitmap := TBitmap.Create;
MyBitmap.Width := 500;
MyBitmap.Height := 500;
MyBitmap.Canvas.Brush.Style := bsSolid;
MyBitmap.Canvas.Brush.Color := clRed;
MyBitmap.Canvas.FillRect(MyRect);

MyTIEBitmap.CopyFromTBitmap(ATBitmap);

procedure TForm1.Button2Click(Sender: TObject);
var
  iIEBitmap: TIEBitmap;
  iIEBitmap2: TIEBitmap;
  iRect: TRect;
begin
  try
    iRect := Rect(0, 0, 250, 250);
    iIEBitmap := TIEBitmap.Create;
    iIEBitmap.Allocate(500, 500);
    iIEBitmap.Canvas.Brush.Style := bsSolid;
    iIEBitmap.Canvas.Brush.Color := clRed;
    iIEBitmap.Canvas.FillRect(iRect);
    try
      iIEBitmap2 := TIEBitmap.Create(iIEBitmap);
      ImageEnView1.IEBitmap.Assign(iIEBitmap2);
      ImageEnView1.Update;
    finally
      iIEBitmap2.Free;
    end;
  finally
    iIEBitmap.Free;
  end;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  iIEBitmap: TIEBitmap;
  iIEBitmap2: TIEBitmap;
  iRect: TRect;
begin
  try
    {Create a white 500x500 IEBitmap}
    iIEBitmap := TIEBitmap.Create;
    iIEBitmap.Allocate(500, 500);
    iIEBitmap.Fill(clWhite);
    {Create a red rect }
    iRect := Rect(0, 0, 250, 250);
    iIEBitmap.Canvas.Brush.Style := bsSolid;
    iIEBitmap.Canvas.Brush.Color := clRed;
    iIEBitmap.Canvas.FillRect(iRect);
    {Create a green rect }
    iRect := Rect(50, 275, 275, 250);
    iIEBitmap.Canvas.Brush.Style := bsSolid;
    iIEBitmap.Canvas.Brush.Color := clGreen;
    iIEBitmap.Canvas.FillRect(iRect);
    {Create a blue rect }
    iRect := Rect(300, 300, 350, 350);
    iIEBitmap.Canvas.Brush.Style := bsSolid;
    iIEBitmap.Canvas.Brush.Color := clBlue;
    iIEBitmap.Canvas.FillRect(iRect);
    try
      iIEBitmap2 := TIEBitmap.Create(iIEBitmap);
      ImageEnView1.IEBitmap.Assign(iIEBitmap2);
      ImageEnView1.Update;
    finally
      iIEBitmap2.Free;
    end;
  finally
    iIEBitmap.Free;
  end;
end;