How to add new matrix dynamically to an image

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C#

VS2012

image-processing

Hello, I am working on image processing(designing a UI) using C#.Net and VS 2012. I have added Convolution filter to my form. I have added a kernel matrix in back-end but now i want to add new matrix(of any size-3*3, 5*5, 7*7 etc) during run time. I don't know what to do and how to do. Can anyone help me, please.
(When we click on the Convolution button a new form appears and asks to enter new matrix. Here I am facing problem, I am unable to design format to enter the matrix in row-column format(creating different cells to enter data)).

What I have tried:

//Code for convolution

private static double[,] kernel
        {
            get
            {
                return new double[,]
                {
                    { 0, 1, 0 },
                    { 1, -4, 1 },
                    { 0, 1, 0 }
                };
            }
        }

        private void btnConvolution_Click(object sender, EventArgs e)
        {
                    newBitmap = (Bitmap)pictureBox1.Image;
                    int width = newBitmap.Width;
                    int height = newBitmap.Height;

                    BitmapData srcData = newBitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
                    int bytes = srcData.Stride * srcData.Height;

                    byte[] buffer = new byte[bytes];//new array
                    byte[] result = new byte[bytes];
                    Marshal.Copy(srcData.Scan0, buffer, 0, bytes);
                    newBitmap.UnlockBits(srcData);
                    int colorChannels = 3;//3 color channels
                    double[] rgb = new double[colorChannels];
                    int foff = (kernel.GetLength(0) - 1) / 2;
                    int kcenter = 0;
                    int kpixel = 0;

                    for (int y = foff; y < height - foff; y++)
                    {
                        for (int x = foff; x < width - foff; x++)
                        {
                            for (int c = 0; c < colorChannels; c++)
                            {
                                rgb[c] = 0.0;
                            }
                            kcenter = y * srcData.Stride + x * 4;
                            for (int fy = -foff; fy <= foff; fy++)
                            {
                                for (int fx = -foff; fx <= foff; fx++)
                                {
                                    kpixel = kcenter + fy * srcData.Stride + fx * 4;
                                    for (int c = 0; c < colorChannels; c++)
                                    {
                                        rgb[c] += (double)(buffer[kpixel + c]) * kernel[fy + foff, fx + foff];
                                    }
                                }
                            }
                            for (int c = 0; c < colorChannels; c++)
                            {
                                if (rgb[c] > 255)
                                {
                                    rgb[c] = 255;
                                }
                                else if (rgb[c] < 0)
                                {
                                    rgb[c] = 0;
                                }
                            }
                            for (int c = 0; c < colorChannels; c++)
                            {
                                result[kcenter + c] = (byte)rgb[c];
                            }
                            result[kcenter + 3] = 255;
                        }
                    }

                    Bitmap resultImage = new Bitmap(width, height);
                    BitmapData resultData = resultImage.LockBits(new Rectangle(0, 0, width, height),
                    ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
                    Marshal.Copy(result, 0, resultData.Scan0, bytes);
                    resultImage.UnlockBits(resultData);

                    newBitmap = (Bitmap)resultImage.Clone();
                    pictureBox1.Image = newBitmap;
                    btnUndo.Enabled = true;
                    undostack.Push(pictureBox1.Image);
                }
        }