var
  x, y:integer;
  MetaFile:TMetaFile;
  MetaCanvas:TCanvas;
  bmp:TIEBitmap;
begin
  // load image with alpha in ImageEnView1
  ImageEnView1.IO.LoadFromFile('myimage.xxx');

  bmp := ImageEnView1.IEBitmap;
  MetaFile := TMetaFile.Create();
  MetaFile.Enhanced := true;
  MetaFile.Width := bmp.Width;
  MetaFile.Height := bmp.Height;
  MetaCanvas := TMetaFileCanvas.Create(MetaFile, 0);
  for y:=0 to bmp.Height-1 do
  begin
    for x:=0 to bmp.Width-1 do
    begin
      if bmp.AlphaChannel.Pixels_ie8[x, y] > 0 then
      begin
        MetaCanvas.Brush.Color := TRGB2TColor(bmp.Pixels[x, y]);
        MetaCanvas.FillRect(Rect(x, y, x+1, y+1));
      end;
    end;
  end;
  MetaCanvas.Free();
  MetaFile.SaveToFile('testmeta.emf');
  MetaFile.Free();
end;