New Post: SkinToneEffect

publicclass SkinToneEffect : IEffect
   {public YCbCrColor LowerThreshold { get; set; }public YCbCrColor UpperThreshold { get; set; }public Color Color { get; set; }publicfloat Amout { get; set; }publicstring Name { get { return"Tone"; } }public SkinToneEffect(Color c, float a)
       {
           LowerThreshold = YCbCrColor.Min;
           UpperThreshold = YCbCrColor.Max;

           Color = c;
           Amout = a;
       }

      ///<summary>/// Processes a bitmap and returns a new processed WriteabelBitmap.///</summary>///<param name="input">The input bitmap.</param>///<returns>The result of WriteabelBitmap processing.</returns>public WriteableBitmap Process(WriteableBitmap input)
      {// Prepare some variablesvar width = input.PixelWidth;var height = input.PixelHeight;return Process(input.Pixels, width, height).ToWriteableBitmap(width, height);
      }///<summary>/// Processes an ARGB32 integer bitmap and returns the new processed bitmap data.///</summary>///<param name="inputPixels">The input bitmap as integer array.</param>///<param name="width">The width of the bitmap.</param>///<param name="height">The height of the bitmap.</param>///<returns>The result of the processing.</returns>publicint[] Process(int[] inputPixels, int width, int height)
      {var resultPixels = newint[inputPixels.Length];// Threshold every pixelfor (int i = 0; i < inputPixels.Length; i++)
          {int c = inputPixels[i];var ycbcr = YCbCrColor.FromArgbColori(c);if (ycbcr.Y >= LowerThreshold.Y && ycbcr.Y <= UpperThreshold.Y&& ycbcr.Cb >= LowerThreshold.Cb && ycbcr.Cb <= UpperThreshold.Cb&& ycbcr.Cr >= LowerThreshold.Cr && ycbcr.Cr <= UpperThreshold.Cr)
              {// skin tone match 
                  System.Windows.Media.Color sc = System.Windows.Media.Color.FromArgb((byte)(c >> 24), (byte)(c >> 16), (byte)(c >> 8), (byte)c);

                  Microsoft.Xna.Framework.Color xc = new Microsoft.Xna.Framework.Color(sc.R, sc.G, sc.B, sc.A);
                  xc = Color.Lerp(xc, Color, Amout);

                  c = (255 << 24) | ((byte)(xc.R > 255 ? 255 : xc.R) << 16) | ((byte)(xc.G > 255 ? 255 : xc.G) << 8) | (byte)(xc.B > 255 ? 255 : xc.B);
              }
              resultPixels[i] = c;
          }return resultPixels;
      }
   }

///<summary>/// YCbCr color representation./// Y in the reange [0, 1]./// Cb in the reange [-0.5, 0.5]./// Cr in the reange [-0.5, 0.5]./// According to http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC28///</summary>publicclass YCbCrColor
    {publicstatic YCbCrColor Min { get { returnnew YCbCrColor(0, -0.5f, -0.5f); } }publicstatic YCbCrColor Max { get { returnnew YCbCrColor(1, 0.5f, 0.5f); } }publicdouble Y { get; set; }publicdouble Cb { get; set; }publicdouble Cr { get; set; }public YCbCrColor(double y, double cb, double cr)
        {
            Y = y;
            Cb = cb;
            Cr = cr;
        }publicvoid Modify(double brightness, double blue, double red)
        {this.Y = Math.Min(Math.Max(this.Y + brightness, 0), 1);this.Cb = Math.Min(Math.Max(this.Cb + blue, -0.5), 0.5);this.Cr = Math.Min(Math.Max(this.Cr + red, -0.5), 0.5);
        }public Color ToArgbColor()
        {int c = ToArgbColori();return Color.FromArgb((byte)(c >> 24), (byte)(c >> 16), (byte)(c >> 8), (byte)c);
        }publicint ToArgbColori()
        {// Convert to RGBvar r = (Y + 1.402f * Cr) * 255;var g = (Y - 0.344136f * Cb - 0.714136f * Cr) * 255;var b = (Y + 1.772f * Cb) * 255;return (255 << 24) | ((byte)(r > 255 ? 255 : r) << 16) | ((byte)(g > 255 ? 255 : g) << 8) | (byte)(b > 255 ? 255 : b);
        }public YCbCrColor Interpolate(YCbCrColor c2, float amount)
        {returnnew YCbCrColor(Y + (c2.Y - Y) * amount,
                                    Cb + (c2.Cb - Cb) * amount,
                                    Cr + (c2.Cr - Cr) * amount);
        }publicstatic YCbCrColor FromRgb(byte r, byte g, byte b)
        {// Create new YCbCr color from rgb colorconstfloat f = 1f / 255f;var rf = r * f;var gf = g * f;var bf = b * f;var y = 0.299f * rf + 0.587f * gf + 0.114f * bf;var cb = -0.168736f * rf + -0.331264f * gf + 0.5f * bf;var cr = 0.5f * rf + -0.418688f * gf + -0.081312f * bf;returnnew YCbCrColor(y, cb, cr);
        }publicstatic YCbCrColor FromArgbColor(Color color)
        {return FromRgb(color.R, color.G, color.B);
        }publicstatic YCbCrColor FromArgbColori(int color)
        {return FromRgb((byte)(color >> 16), (byte)(color >> 8), (byte)(color));
        }
    }
Most of it is Rene's code (mix and match :)) Sorry Rene

Based on my post at http://wp.me/p1FGGY-8E