Accord.Imaging.Filters.HSLFiltering.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;

            RGB rgb = new RGB();
            HSL hsl = new HSL();

            bool updated;

            // 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)
                {
                    updated = false;
                    rgb.Red = ptr[RGB.R];
                    rgb.Green = ptr[RGB.G];
                    rgb.Blue = ptr[RGB.B];

                    // convert to HSL
                    Accord.Imaging.HSL.FromRGB(rgb, hsl);

                    // check HSL values
                    if (
                        (hsl.Saturation >= saturation.Min) && (hsl.Saturation <= saturation.Max) &&
                        (hsl.Luminance >= luminance.Min) && (hsl.Luminance <= luminance.Max) &&
                        (
                        ((hue.Min < hue.Max) && (hsl.Hue >= hue.Min) && (hsl.Hue <= hue.Max)) ||
                        ((hue.Min > hue.Max) && ((hsl.Hue >= hue.Min) || (hsl.Hue <= hue.Max)))
                        )
                        )
                    {
                        if (!fillOutsideRange)
                        {
                            if (updateH) hsl.Hue = fillH;
                            if (updateS) hsl.Saturation = fillS;
                            if (updateL) hsl.Luminance = fillL;

                            updated = true;
                        }
                    }
                    else
                    {
                        if (fillOutsideRange)
                        {
                            if (updateH) hsl.Hue = fillH;
                            if (updateS) hsl.Saturation = fillS;
                            if (updateL) hsl.Luminance = fillL;

                            updated = true;
                        }
                    }

                    if (updated)
                    {
                        // convert back to RGB
                        Accord.Imaging.HSL.ToRGB(hsl, rgb);

                        ptr[RGB.R] = rgb.Red;
                        ptr[RGB.G] = rgb.Green;
                        ptr[RGB.B] = rgb.Blue;
                    }
                }
                ptr += offset;
            }
        }
    }