[NumLock]

Код:

var
  path: String;
  searchrec: TSearchRec;
  ext: String;
  image: TImage;
  n: Integer;
begin
  Randomize;
  n:=0;
  path:=IncludeTrailingPathDelimiter(Edit1.Text);
  if FindFirst(path+'*.*', 0, searchrec)=0 then
  begin
    repeat
      if (searchrec.Attr and faDirectory)=0 then
      begin
        ext:=LowerCase(ExtractFileExt(searchrec.Name));
        if (ext='.jpeg') or (ext='.jpg') or (ext='.bmp') then
        begin
          image:=TImage.Create(Self);
          image.Parent:=Self;
          image.AutoSize:=False;
          image.Stretch:=True;
          image.Width:=120;
          image.Height:=120;
          image.Left:=Random(ClientWidth)-image.Width;
          image.Top:=Random(ClientHeight)-image.Height;
          image.Picture.LoadFromFile(path+searchrec.Name);
          Application.ProcessMessages;
          Inc(n);
          if n>50 then Break;
        end;
      end;
    until FindNext(searchrec)<>0;
    FindClose(searchrec);
  end;

полный пример