procedure TForm1.Button1Click(Sender: TObject);
var
  fileheader: TBitmapfileheader;
  infoheader: TBitmapinfoheader;
  s: TFilestream;
  aFile : String;
begin
  aFile := 'C:\Benutzer\Orchidee.bmp';
  s := TFileStream.Create(aFile, fmOpenRead);
  try
    s.Read(fileheader, SizeOf(fileheader));
    //Nach dem filehaeder beginnt der infoheader
    s.Read(infoheader, SizeOf(infoheader));

    Form1.Label1.Caption := 'Width: ' 
                            + FormatFloat('#,##0' 
                            ,StrToFloat(IntToStr(infoheader.biWidth)));
    if infoheader.biHeight >=0 then
      Form1.Label2.Caption := 'Height: ' 
                              + FormatFloat('#,##0' 
                              ,StrToFloat(IntToStr(infoheader.biHeight)))
      else
        Form1.Label2.Caption := 'Height: ' 
                                + FormatFloat('#,##0' 
                                ,StrToFloat(IntToStr(infoheader.biHeight)))
                                +' (Top-down-DIB)';

  finally
    s.Free;
  end;
end;