program GetScrnJpg;

uses
  Windows, Graphics, jpeg;

{$R *.RES}

var
  B: TBitmap;
  S: string;

begin

  B := TBitmap.Create;

  B.Width := GetSystemMetrics(SM_CXSCREEN);    {Screen.Width}
  B.Height := GetSystemMetrics(SM_CYSCREEN);   {Screen.Height}

  BitBlt(B.Canvas.handle, 0, 0, B.Width, B.Height, GetDc(0), 0, 0, SRCCOPY);


  if ParamStr(1) <> '' then
    S := ParamStr(1) + '.jpg'
  else
    S := 'Screen.jpg';

  with TJPEGImage.Create do
    begin
      Assign(B);
      CompressionQuality := 75;
      SaveToFile(S);
      free;
    end;

  B.Free;

end.