Accord.Imaging.Filters.ChannelFiltering.ProcessFilter C# (CSharp) Method

        protected override unsafe void ProcessFilter(UnmanagedImage image, Rectangle rect)
        {
            // get pixel size
            int pixelSize = (image.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;

            int startX = rect.Left;
            int startY = rect.Top;
            int stopX = startX + rect.Width;
            int stopY = startY + rect.Height;
            int offset = image.Stride - rect.Width * pixelSize;

            // do the job
            byte* ptr = (byte*)image.ImageData.ToPointer();

            // allign pointer to the first pixel to process
            ptr += (startY * image.Stride + startX * pixelSize);

            // for each row
            for (int y = startY; y < stopY; y++)
            {
                // for each pixel
                for (int x = startX; x < stopX; x++, ptr += pixelSize)
                {
                    // red
                    ptr[RGB.R] = mapRed[ptr[RGB.R]];
                    // green
                    ptr[RGB.G] = mapGreen[ptr[RGB.G]];
                    // blue
                    ptr[RGB.B] = mapBlue[ptr[RGB.B]];
                }
                ptr += offset;
            }
        }