procedure TfrmMainForm.scBtnSelSkinColorClick(Sender: TObject);
var
  X, Y: Integer;
  Clr: TRGB;
  R,G,B: Integer;
  arrClrVal: array[0..2] of Integer;
begin
  ImageEnViewMain.Deselect;
  ImageEnViewMain.SelectionMaskDepth := 8;
  if (ImageEnViewMain.IEBitmap.Width > 100) and (ImageEnViewMain.IEBitmap.Height > 0) then
  begin
    for Y := 0 to ImageEnViewMain.IEBitmap.Height - 1 do
    begin
      for X := 0 to ImageEnViewMain.IEBitmap.Width - 1 do
      begin
        Clr := ImageEnViewMain.IEBitmap.Pixels[X,Y];
        R := Clr.r;
        G := Clr.g;
        B := Clr.b;

        arrClrVal[0] := R;
        arrClrVal[1] := G;
        arrClrVal[2] := B;        

        if ((R > 95) and (G > 40) and (B > 20) and ((MaxIntValue(arrClrVal) - MinIntValue(arrClrVal)) > 15) and ((r - g) > 15) and (R > G) and (R > B)) then
        begin
          ImageEnViewMain.SelectionMask.SetPixel(X,Y,1);
        end;
      end;
    end;
    ImageEnViewMain.SelectCustom;
    ImageEnViewMain.Proc.DoPreviews(ppeColorAdjust);
  end;
end;

// Make a gradient selection (increasing from unselected to fully selected along height of image)
// Then convert selection to gray scale
ImageEnView1.Deselect();
ImageEnView1.SelectionMaskDepth := 8;
for Y := 0 to ImageEnView1.IEBitmap.Height - 1 do
  for X := 0 to ImageEnView1.IEBitmap.Width - 1 do
  begin
    selIntensity := Round( Y / ImageEnView1.IEBitmap.Height * 255 );
    ImageEnView1.SelectionMask.SetPixel( X, Y, selIntensity );
  end;
ImageEnView1.SelectCustom;
ImageEnView1.Proc.ConvertToGray();
ImageEnView1.Deselect();