procedure processPixel(rgb: PRGB);
var
  d, r, g: double;
  F1, F2: double;
  w: double;
  isSkin: boolean;
  h, s, l: integer;
begin
  d := (rgb^.r + rgb^.g + rgb^.b);
  if d > 0 then
  begin
    r := rgb^.r / d;
    g := rgb^.g / d;
  end
  else
  begin
    r := 0;
    g := 0;
  end;
  F1 := -1.376 * sqr(r) +1.0743 * r + 0.2;
  F2 := -0.776 * sqr(r) +0.5601 * r + 0.18;
  w := sqr(r - 0.33) + sqr(g - 0.33);
  isSkin := (g < F1) and (g > F2) and (w > 0.001);

  RGB2HSV(rgb^, h, s, l);

  isSkin := isSkin and ((h > 240) or (h <= 50));  

  if not isSkin then
    rgb^ := CreateRGB(0, 0, 0);
end;

procedure TForm1.Button22Click(Sender: TObject);
var
  i, j: integer;
begin
  ImageEnView1.IO.LoadFromFile('input.jpg');

  for i := 0 to ImageEnView1.IEBitmap.Height - 1 do
    for j := 0 to ImageEnView1.IEBitmap.Width - 1 do
      processPixel( ImageEnView1.IEBitmap.PPixels_ie24RGB[j, i] );

  ImageEnView1.Update();
end;