Accord.Imaging.Filters.LevelsLinear16bpp.ProcessFilter C# (CSharp) Method

        protected override unsafe void ProcessFilter(UnmanagedImage image, Rectangle rect)
        {
            int pixelSize = Image.GetPixelFormatSize(image.PixelFormat) / 16;

            // processing start and stop X,Y positions
            int startX = rect.Left;
            int startY = rect.Top;
            int stopX = startX + rect.Width;
            int stopY = startY + rect.Height;

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

            if (image.PixelFormat == PixelFormat.Format16bppGrayScale)
            {
                // grayscale image
                for (int y = startY; y < stopY; y++)
                {
                    ushort* ptr = (ushort*)(basePtr + y * image.Stride) + startX;

                    for (int x = startX; x < stopX; x++, ptr++)
                    {
                        // gray
                        *ptr = mapGreen[*ptr];
                    }
                }
            }
            else
            {
                // RGB image
                for (int y = startY; y < stopY; y++)
                {
                    ushort* ptr = (ushort*)(basePtr + y * image.Stride) + startX * pixelSize;

                    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]];
                    }
                }
            }
        }