program x4;

uses SysUtils, Classes, Graphics, Jpeg;

var
 j: TJpegImage;
 b: TBitmap;
 i: Integer;
 FileName: string;
 List: TStringList;
 SR: TSearchRec;

 procedure Convert(const FileName:string);
 begin
   j.LoadFromFile(FileName);
   b.Assign(j);
   j.Assign(b);
   j.SaveToFile('x4_'+FileName);
 end;

begin
 j := TJpegImage.Create;
 j.Scale := jsQuarter;
 b := TBitmap.Create;
 if ParamCount = 0 then begin
   List := TStringList.Create;
   if FindFirst('*.jpg', faAnyFile, SR) = 0 then begin
     repeat
       List.Add(SR.Name);
     until FindNext(SR) <> 0;
     FindClose(SR);
   end;
   for i := 0 to List.Count - 1 do
     Convert(List[i]);
   List.Free;
 end
 else
   for i := 1 to ParamCount do begin
     FileName := ParamStr(i);
     if FileExists(FileName) and
       (LowerCase(ExtractFileExt(FileName)) = '.jpg') then
         Convert(FileName);
   end;
 j.Free;
 b.Free;
end.