ParamCount ParamStr ExtractFileExt(picPath)

procedure TForm1.FormCreate(Sender: TObject);
var
 picPath:string;
 ext:string;
begin
//showmessage(inttostr(ParamCount)+ParamStr(1));
if ( ParamCount = 0 ) then
begin
  //Application.Terminate;
  exit;
end;
 picPath:=ParamStr(1);
 ext:=ExtractFileExt(picPath);
 ext:=UpperCase(ext);
 showmessage(ext);
 //if ext then ...
 Image1.Picture.LoadFromFile(picPath);
end;

end.