Darken Image (Degrade)

Face You Can Convert to Bitmap and Move the pixel array pixel to pixel by changing the value of in RGB Proportionally, There may be one component but I do not know and another that installing many components is not legal, projects can be discontinued and some methods you can migrate from version to version.

    function  TForm1.GrayScale (Imagem : TBitmap) : TBitmap;
    var Gray : TBitmap;
    i, j : Integer;
    Pixel : TColor;
    GrayScale : Integer;
    Red, Green, Blue : Double;
    begin
      Gray        := TBitmap.Create;
      Gray.Height := Imagem.Height;
      Gray.Width  := Imagem.Width;

      for i := 0 to Imagem.Height do
      begin
        for j := 0 to Imagem.Width do
        begin
          Pixel := Imagem.Canvas.Pixels[j,i];

          Red   := GetRValue(Pixel);
          Green := GetGValue(Pixel);
          Blue  := GetBValue(Pixel);

          GrayScale := Trunc((Red * 0.3) + (Green * 0.59) + (Blue * 0.0011));
          Gray.Canvas.Pixels[j,i] := RGB(Byte(GrayScale), Byte(GrayScale),          Byte(GrayScale));
            end;
        end;
           Result := Gray;
        end;

This Example code changes to grayscale to arrive at the hue you want you can change the values that multiply the RGB.