{ ... }
try
 try
  begin
  b := TBitmap.Create;
  tBufr := TBitmap.Create;
  CopyMe(b, Image1.Picture.Graphic); {copy image to b}
  Twist(100);
  end;
 finally
  begin
  b.Free;
  tBufr.Free;
  end;
 end;
except
 raise ESomeErrorWarning.Create('Kaboom!');
end;
{ ... }

{A procedure to copy a graphic to a bitmap}

procedure TForm1.CopyMe(tobmp: TBitmap; frbmp: TGraphic);

begin

 tobmp.PixelFormat := pf24bit;

 tobmp.Width := frbmp.Width;

 tobmp.Height := frbmp.Height;

 tobmp.Canvas.Draw(0, 0, frbmp);

end;

procedure TForm1.Twist(Amount: integer);

var

 fxmid, fymid: Single;

 txmid, tymid: Single;

 fx, fy: Single;

 tx2, ty2: Single;

 r: Single;

 theta: Single;

 ifx, ify: Integer;

 dx, dy: Single;

 K: integer;

 Offset: Single;

 ty, tx: Integer;

 weight_x, weight_y: array[0..1] of Single;

 weight: Single;

 new_red, new_green: Integer;

 new_blue: Integer;

 total_red, total_green: Single;

 total_blue: Single;

 ix, iy: Integer;

 sli, slo: pRGBArray;

 function ArcTan2(xt, yt: Single): Single;

 begin

  if xt = 0 then

  if yt > 0 then

  Result := Pi / 2

  else

  Result := -(Pi / 2)

  else

  begin

  Result := ArcTan(yt / xt);

  if xt < 0 then

  Result := Pi + ArcTan(yt / xt);

  end;

 end;

begin

 Screen.Cursor := crHourGlass;

 CopyMe(tBufr, b);

 K := Amount; {Adjust this for 'amount' of twist}

 Offset := -(Pi / 2);

 dx := b.Width - 1;

 dy := b.Height - 1;

 r := Sqrt(dx * dx + dy * dy);

 tx2 := r;

 ty2 := r;

 txmid := (b.Width - 1) / 2; {Adjust these to move center of rotation}

 tymid := (b.Height - 1) / 2; {Adjust these to move}

 fxmid := (b.Width - 1) / 2;

 fymid := (b.Height - 1) / 2;

 if tx2 >= b.Width then

  tx2 := b.Width - 1;

 if ty2 >= b.Height then

  ty2 := b.Height - 1;

 for ty := 0 to Round(ty2) do

 begin

  for tx := 0 to Round(tx2) do

  begin

  dx := tx - txmid;

  dy := ty - tymid;

  r := Sqrt(dx * dx + dy * dy);

  if r = 0 then

  begin

  fx := 0;

  fy := 0;

  end

  else

  begin

  theta := ArcTan2(dx, dy) - r / K - Offset;

  fx := r * Cos(theta);

  fy := r * Sin(theta);

  end;

  fx := fx + fxmid;

  fy := fy + fymid;

  ify := Trunc(fy);

  ifx := Trunc(fx);

  {Calculate the weights}

  if fy >= 0 then

  begin

  weight_y[1] := fy - ify;

  weight_y[0] := 1 - weight_y[1];

  end

  else

  begin

  weight_y[0] := -(fy - ify);

  weight_y[1] := 1 - weight_y[0];

  end;

  if fx >= 0 then

  begin

  weight_x[1] := fx - ifx;

  weight_x[0] := 1 - weight_x[1];

  end

  else

  begin

  weight_x[0] := -(fx - ifx);

  Weight_x[1] := 1 - weight_x[0];

  end;

  if ifx < 0 then

  ifx := b.Width - 1 - (-ifx mod b.Width)

  else if ifx > b.Width - 1 then

  ifx := ifx mod b.Width;

  if ify < 0 then

  ify := b.Height - 1 - (-ify mod b.Height)

  else if ify > b.Height - 1 then

  ify := ify mod b.Height;

  total_red := 0.0;

  total_green := 0.0;

  total_blue := 0.0;

  for ix := 0 to 1 do

  begin

  for iy := 0 to 1 do

  begin

  if ify + iy < b.Height then

  sli := tBufr.Scanline[ify + iy]

  else

  sli := tBufr.ScanLine[b.Height - ify - iy];

  if ifx + ix < b.Width then

  begin

  new_red := sli[ifx + ix].rgbtRed;

  new_green := sli[ifx + ix].rgbtGreen;

  new_blue := sli[ifx + ix].rgbtBlue;

  end

  else

  begin

  new_red := sli[b.Width - ifx - ix].rgbtRed;

  new_green := sli[b.Width - ifx - ix].rgbtGreen;

  new_blue := sli[b.Width - ifx - ix].rgbtBlue;

  end;

  weight := weight_x[ix] * weight_y[iy];

  total_red := total_red + new_red * weight;

  total_green := total_green + new_green * weight;

  total_blue := total_blue + new_blue * weight;

  end;

  end;

  slo := b.ScanLine[ty];

  slo[tx].rgbtRed := Round(total_red);

  slo[tx].rgbtGreen := Round(total_green);

  slo[tx].rgbtBlue := Round(total_blue);

  end;

 end;

 Image1.Picture.Assign(b);

 Screen.Cursor := crDefault;

end;