AForge.Imaging.HSL.FromRGB C# (CSharp) Method

        public static void FromRGB( RGB rgb, HSL hsl )
        {
            float r = ( rgb.Red   / 255.0f );
            float g = ( rgb.Green / 255.0f );
            float b = ( rgb.Blue  / 255.0f );

            float min = Math.Min( Math.Min( r, g ), b );
            float max = Math.Max( Math.Max( r, g ), b );
            float delta = max - min;

            // get luminance value
            hsl.Luminance = ( max + min ) / 2;

            if ( delta == 0 )
            {
                // gray color
                hsl.Hue = 0;
                hsl.Saturation = 0.0f;
            }
            else
            {
                // get saturation value
                hsl.Saturation = ( hsl.Luminance <= 0.5 ) ? ( delta / ( max + min ) ) : ( delta / ( 2 - max - min ) );

                // get hue value
                float hue;

                if ( r == max )
                {
                    hue = ( ( g - b ) / 6 ) / delta;
                }
                else if ( g == max )
                {
                    hue = ( 1.0f / 3 ) + ( ( b - r ) / 6 ) / delta; 
                }
                else
                {
                    hue = ( 2.0f / 3 ) + ( ( r - g ) / 6 ) / delta;
                }

                // correct hue if needed
                if ( hue < 0 )
                    hue += 1;
                if ( hue > 1 )
                    hue -= 1;

                hsl.Hue = (int) ( hue * 360 );
            }
        }

        private unsafe void ProcessImage(UnmanagedImage image)
        {
            this.CheckSourceFormat(image.PixelFormat);
            int width  = image.Width;
            int height = image.Height;

            this.pixels = this.pixelsWithoutBlack = 0;
            int[] numArray  = new int[0x100];
            int[] numArray2 = new int[0x100];
            int[] numArray3 = new int[0x100];
            int[] numArray4 = new int[0x100];
            RGB   rgb       = new RGB();
            HSL   hsl       = new HSL();
            int   num3      = (image.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;
            int   num4      = image.Stride - (width * num3);
            byte *numPtr    = (byte *)image.ImageData.ToPointer();

            for (int i = 0; i < height; i++)
            {
                int num6 = 0;
                while (num6 < width)
                {
                    rgb.Red   = numPtr[2];
                    rgb.Green = numPtr[1];
                    rgb.Blue  = numPtr[0];
                    HSL.FromRGB(rgb, hsl);
                    numArray[(int)(hsl.Saturation * 255.0)]++;
                    numArray2[(int)(hsl.Luminance * 255.0)]++;
                    this.pixels++;
                    if (hsl.Luminance != 0.0)
                    {
                        numArray3[(int)(hsl.Saturation * 255.0)]++;
                        numArray4[(int)(hsl.Luminance * 255.0)]++;
                        this.pixelsWithoutBlack++;
                    }
                    num6++;
                    numPtr += num3;
                }
                numPtr += num4;
            }
            this.saturation             = new ContinuousHistogram(numArray, new DoubleRange(0.0, 1.0));
            this.luminance              = new ContinuousHistogram(numArray2, new DoubleRange(0.0, 1.0));
            this.saturationWithoutBlack = new ContinuousHistogram(numArray3, new DoubleRange(0.0, 1.0));
            this.luminanceWithoutBlack  = new ContinuousHistogram(numArray4, new DoubleRange(0.0, 1.0));
        }