Разрезать JPEG на 12 равных частей

uses
  JPEG;

type
  TBitMaps = array of TBitMap;

procedure BitMapsFree(var BitMaps: TBitMaps);
var
  i: Integer;
begin
  for i := 0 to High(BitMaps) do begin
    BitMaps.Free;
  end;
  SetLength(BitMaps, 0);
end;

function JPEGSlices(const FileName: string; Rows, Cols: Integer): TBitMaps;
var
  jpg: TJPEGImage;
  bmp: TBitMap;
  Width, Height: Integer;
  i, j, idx, x, y: Integer;
begin
  jpg := TJPEGImage.Create;
  jpg.LoadFromFile(FileName);
  bmp := TBitMap.Create;
  bmp.Assign(jpg);
  jpg.Free;
  Width := bmp.Width div Cols;
  Height := bmp.Height div Rows;
  SetLength(Result, Rows * Cols);
  idx := 0;
  for i := 0 to Rows - 1 do begin
    y := i * Height;
    for j := 0 to Cols - 1 do begin
      x := j * Width;
      Result[idx] := TBitMap.Create;
      Result[idx].Width := Width;
      Result[idx].Height := Height;
      Result[idx].Canvas.CopyRect(
        Rect(0, 0, Width - 1, Height - 1),
        bmp.Canvas,
        Rect(x, y, x + Width - 1, y + Height - 1)
      );
      inc(idx);
    end;
  end;
  bmp.Free;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Images: TBitMaps;
  i, x: Integer;
begin
  Images := JPEGSlices('test.jpg', 2, 6);
  x := 20;
  for i := 0 to High(Images) do begin
    Canvas.Draw(x, 100, Images);
    inc(x, Images.Width + 2);
  end;
  BitMapsFree(Images);
end;