procedure TForm1.Button1Click(Sender: TObject);
var
  jpg :TJpegImage;
  bmp,tmpbmp :TBitmap;
begin
  jpg :=TJpegImage.Create;
  jpg.LoadFromFile('h:\d006-38\dscn0001.jpg');
  bmp :=TBitmap.Create;
  bmp.Assign(jpg);
  tmpbmp :=TBitmap.Create;
  tmpbmp.Width :=120;//bmp.Width div 2;
  tmpbmp.Height :=90;//bmp.Height div 2;
  tmpbmp.pixelformat:=pf32bit;
  jpg.PixelFormat:=jf24bit;
//  tmpbmp.canvas.streahdraw( jpg.picture.bitmap);
  tmpbmp.Canvas.StretchDraw(tmpbmp.Canvas.ClipRect,jpg);
  
{  StretchBlt(tmpbmp.Canvas.Handle,0,0,tmpbmp.Width,tmpbmp.Height,
              bmp.Canvas.Handle,0,0,bmp.Width,bmp.Height,SRCCOPY);
}
  jpg.Assign(tmpbmp);
  jpg.SaveToFile('d:\12.jpg');
  jpg.Free;
  bmp.Free;
  tmpbmp.Free;
end;