public void Suwak(int WARTOSC)
        {
            System.Drawing.Color pixel;
            double J = 0;
            double C = 0;
            for (int j = 1; j <= L; j++)
                for (int i = 1; i <= K; i++)
                {
                    pixel = m_obraz_w_pamieci.GetPixel(i - 1, j - 1);

                    //--------------------------------------//
                    int R = WARTOSC + pixel.R;
                    R = Math.Min(255, R);
                    R = Math.Max(0, R);

                    int G = WARTOSC + pixel.G;
                    G = Math.Min(255, G);
                    G = Math.Max(0, G);

                    int B = WARTOSC + pixel.B;
                    B = Math.Min(255, B);
                    B = Math.Max(0, B);

                    J += (R + G + B) / 3;

                    pixel = System.Drawing.Color.FromArgb(R, G, B);

                    //--------------------------------------//

                    m_ekran.SetPixel(i - 1, j - 1, pixel);
                }
            J = J / (L * K);
            for (int j = 1; j <= L; j++)
                for (int i = 1; i <= K; i++)
                {
                    pixel = m_obraz_w_pamieci.GetPixel(i - 1, j - 1);
                    int R = WARTOSC + pixel.R;
                    R = Math.Min(255, R);
                    R = Math.Max(0, R);

                    int G = WARTOSC + pixel.G;
                    G = Math.Min(255, G);
                    G = Math.Max(0, G);

                    int B = WARTOSC + pixel.B;
                    B = Math.Min(255, B);
                    B = Math.Max(0, B);

                    C += (((R + G + B) / 3) - J) * (((R + G + B) / 3) - J);
                }
            J = 100 * J / 255;
            C = 100 * Math.Sqrt(C) / (L * 127.5);

            label1.Text = "Jasnosc = " + ((double)J).ToString("00.00") + "%";
            label2.Text = "Kontrast = " + ((double)C).ToString("00.00") + "%";

            SetBitMap(ref m_ekran);
        }