} //**************************** end Open image *************************************

        private void button2_Click(object sender, EventArgs e) //  Edge detection
        {
            if (OPEN == false)
            {
                MessageBox.Show("Please open an image");
                return;
            }
            if (!radioButton1.Checked && !radioButton2.Checked)
            {
                MessageBox.Show("Please click one of the radio buttons on the left side");
                return;
            }

            progressBar1.Visible = true;
            progressBar1.Value   = 0;

            progressBar1.Visible = true;
            SigmaIm.SigmaSimpleUni(OrigIm, 1, 30, this);
            ExtremIm.ExtremLightUni(SigmaIm, 3, this);

            Threshold = (int)numericUpDown1.Value;
            int NX = OrigIm.width;

            CombIm.LabelCellsSign(Threshold, ExtremIm, this);

            CombIm.CleanCombNew(81, this);

            int rv = CombIm.CheckComb(this);

            if (rv < 0)
            {
                Application.Exit();
            }

            EdgeIm.CracksToPixel(CombIm);

            // The image "CombIm" gets the pixel values as lightnes (MaxC) of pixels of "ExtremIm"
            for (int y = 0; y < OrigIm.height; y++)
            {
                for (int x = 0; x < OrigIm.width; x++)
                {
                    CombIm.Grid[2 * x + 1 + (2 * NX + 1) * (2 * y + 1)] =
                        CombIm.MaxC(ExtremIm.Grid[3 * (x + NX * y) + 2], ExtremIm.Grid[3 * (x + NX * y) + 1], ExtremIm.Grid[3 * (x + NX * y) + 0]);
                }
            }

            EdgeIm.nLoop     = nLoop;
            EdgeIm.denomProg = denomProg;
            EdgeIm.ImageToBitmapOld(BmpPictBox2, this);
            pictureBox2.Refresh();

            progressBar1.Visible = false;

            label6.Visible         = true;
            label6.Text            = "Detected edges";
            button3.Visible        = true;
            label2.Visible         = true;
            numericUpDown2.Visible = true;
            label7.Text            = "Click 'Pollygons'";
            label7.Visible         = true;
            if (PanelWithGrid != null)
            {
                PanelWithGrid.Dispose();
            }

            EDGES = true;
        } //*************************** end edge detection ******************************