Aforge.net Background Subtraction/Extraction

using AForge.Imaging;
using AForge.Imaging.Filters;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;

namespace ISpyFilterTest.service.camera.filter {
    public class ColorMaskFilter : BaseInPlacePartialFilter {
        #region Init
        private Dictionary<PixelFormat, PixelFormat> formatTranslations;
        private Bitmap mask;
        public override Dictionary<PixelFormat, PixelFormat> FormatTranslations { get { return formatTranslations; } }
        private int maxDiferenceRed;
        private int maxDiferenceGreen;
        private int maxDiferenceBlue;

        public ColorMaskFilter(Bitmap mask) : this(mask, 50) { }
        public ColorMaskFilter(Bitmap mask, int maxDiferenceColor) : this(mask, maxDiferenceColor, maxDiferenceColor, maxDiferenceColor) { }
        public ColorMaskFilter(Bitmap mask, int maxDiferenceRed, int maxDiferenceGreen, int maxDiferenceBlue) {
            formatTranslations = new Dictionary<PixelFormat, PixelFormat>();
            formatTranslations[PixelFormat.Format24bppRgb] = PixelFormat.Format24bppRgb;
            formatTranslations[PixelFormat.Format32bppRgb] = PixelFormat.Format32bppRgb;
            formatTranslations[PixelFormat.Format32bppArgb] = PixelFormat.Format32bppArgb;

            this.mask = mask;
            this.maxDiferenceRed = maxDiferenceRed;
            this.maxDiferenceGreen = maxDiferenceGreen;
            this.maxDiferenceBlue = maxDiferenceBlue;
        }
        #endregion

        protected unsafe override void ProcessFilter(UnmanagedImage uImage, Rectangle rect) {
            int pixelSize = System.Drawing.Image.GetPixelFormatSize(uImage.PixelFormat) / 8;
            var src = (byte*)uImage.ImageData.ToPointer();

            mask.Unmanaged(mUImage => {
                var msk = (byte*)mUImage.ImageData.ToPointer();

                var size = uImage.Width * uImage.Height;
                while (size-- > 0) {
                    var rSrcp = src + 2; var rMskp = msk + 2;
                    var gSrcp = src + 1; var gMskp = msk + 1;
                    var bSrcp = src + 0; var bMskp = msk + 0;

                    if (
                        Math.Abs(*rSrcp - *rMskp) <= maxDiferenceRed &&
                        Math.Abs(*gSrcp - *gMskp) <= maxDiferenceGreen &&
                        Math.Abs(*bSrcp - *bMskp) <= maxDiferenceBlue
                    ) {
                        *rSrcp = 0;
                        *gSrcp = 0;
                        *bSrcp = 0;
                    }

                    src += pixelSize;
                    msk += pixelSize;
                }
            }, ImageLockMode.ReadOnly);
        }
    }
}

using AForge.Imaging;
using System;
using System.Drawing;
using System.Drawing.Imaging;

namespace ISpyFilterTest.service {
    public static class BitmapExt {

        public static void Unmanaged(this Bitmap image, Action<UnmanagedImage> action, ImageLockMode lockMode = ImageLockMode.ReadWrite) {
            var imageData = image.LockBits(new Rectangle(0, 0, image.Width, image.Height), lockMode, image.PixelFormat);
            try {
                var uImage = new UnmanagedImage(imageData);
                action(uImage);
            } catch (Exception) {
                throw;
            } finally {
                image.UnlockBits(imageData);
            }
        }

    }
}