sobel

        public static Bitmap SobelFilter(Bitmap original)
        {
            int[][] Gx = new int[][] { //maska po X
                new int[] {-1,0,1},
                new int[] {-2,0,2},
                new int[] {-1,0,1},
            };
            int[][] Gy = new int[][] { //maska po Y
                new int[] {1,2,1},
                new int[] {0,0,0},
                new int[] {-1,-2,-1},
            };
            Bitmap output = new Bitmap(original);
            FastBitmap temp = new FastBitmap(output); //FastBitmap - szybsze obrabianie pikseli
            FastBitmap input = new FastBitmap(original);
            temp.LockImage();
            input.LockImage();

            for (int i = 1; i < original.Height - 1; i++) //pętla po wierszach
            {
                for (int j = 1; j < original.Width - 1; j++)   //pętla po kolumnach (już konkretny pixel)
                {
                    double new_x = 0, new_y = 0;
                    double c;
                    for (int hw = -1; hw < 2; hw++) //po macierzy
                    {
                        for (int wi = -1; wi < 2; wi++)
                        {
                            c = input.GetPixel(j + wi, i + hw).B;
                            new_x += Gx[hw + 1][ wi + 1] * c;
                            new_y += Gy[hw + 1][ wi + 1] * c;
                        }
                    }
                    int value = Convert.ToInt32(Math.Sqrt(new_x * new_x + new_y * new_y))%255;
                    Color tempcolor = Color.FromArgb(value, value, value);
                    temp.SetPixel(j, i, tempcolor);
                }
            }
            temp.UnlockImage();
            input.UnlockImage();
            return output;
        }//