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.