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

        protected override unsafe void ProcessFilter( UnmanagedImage image, Rectangle rect )
        {
            int pixelSize = Bitmap.GetPixelFormatSize( image.PixelFormat ) / 8;

            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( );

            float desaturationChangeFactor = 1.0f + adjustValue;

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

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

                    if ( adjustValue > 0 )
                    {
                        hsl.Saturation += ( 1.0f - hsl.Saturation ) * adjustValue * hsl.Saturation;
                    }
                    else if ( adjustValue < 0 )
                    {
                        hsl.Saturation *= desaturationChangeFactor;
                    }

                    // 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;
            }
        }
    }