about picture editor(image processing)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Imaging;

namespace Lab1___J
{
    public partial class Form1 : Form
    {
        Image file;
        Bitmap bm_image;        
        int i_change;
        float contrast = 0;
        public Form1()
        {
            InitializeComponent();            
        }

        private void RB_contrast_CheckedChanged(object sender, EventArgs e)
        {
            LBL_color1.Text = "Less";
            LBL_color2.Text = "More";
            trackBar1.SetRange(0, 100);
            trackBar1.TickFrequency = 5;            
        }

        private void RB_blackwhite_CheckedChanged(object sender, EventArgs e)
        {
            LBL_color1.Text = "Less";
            LBL_color2.Text = "More";
            trackBar1.SetRange(0, 100);
            trackBar1.TickFrequency = 5;            
        }

        private void RB_tint_CheckedChanged(object sender, EventArgs e)
        {
            trackBar1.SetRange(0, 100);
            trackBar1.TickFrequency = 5;
            LBL_color1.Text = "Red";
            LBL_color2.Text = "Green";            
        }

        private void RB_noise_CheckedChanged(object sender, EventArgs e)
        {
            LBL_color1.Text = "Less";
            LBL_color2.Text = "More";
            trackBar1.SetRange(0, 100);
            trackBar1.TickFrequency = 5;            
        }

        private void BTN_loadpic_Click(object sender, EventArgs e)
        {

            Stream myStream = null;
            OpenFileDialog openFileDialog1 = new OpenFileDialog();

            openFileDialog1.InitialDirectory = "c:\\";
            openFileDialog1.Filter = "Bitmap Files (*.bmp;*.dib)|*.*|JPEG (*.jpg;*.jpeg;*.jpe;*.jfif)|*.* |PNG (*.png)|*.*|GIF (*.gif)|*.*|All files (*.*)|*.*";
            
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    if ((myStream = openFileDialog1.OpenFile()) != null)
                    {
                        using (myStream)
                        {
                            file = Image.FromFile(openFileDialog1.FileName);
                            bm_image = new Bitmap(openFileDialog1.FileName);
                            pictureBox1.Image = file;                            
                        }
                    }
                }
                catch (Exception)
                {
                    MessageBox.Show("Error: Could not read file.", "PicBender", 
                        MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        private void trackBar1_Scroll(object sender, EventArgs e)
        {
            lbl_Tracknum.Text = trackBar1.Value.ToString();
            i_change = int.Parse(trackBar1.Value.ToString());
        }

        private void BTN_transform_Click(object sender, EventArgs e)
        {
            bm_image = new Bitmap(pictureBox1.Image);
            if (RB_contrast.Checked)
            {
                contrast = 0.04f * trackBar1.Value;

                Bitmap bm = new Bitmap(bm_image.Width, bm_image.Height);

                Graphics g = Graphics.FromImage(bm);

                ImageAttributes ia = new ImageAttributes();

                ColorMatrix cm = new ColorMatrix(new float[][]{
                new float[]{contrast, 0f, 0f, 0f, 0f,},
                new float[]{0f,contrast, 0f, 0f, 0f,},
                new float[]{0f, 0f,contrast, 0f, 0f,},
                new float[]{0f, 0f, 0f, 1f,0f},
                new float[]{0.001f,0.001f,0.001f,0f,1f}});

                ia.SetColorMatrix(cm);

                g.DrawImage(bm_image, new Rectangle(0, 0, bm_image.Width, bm_image.Height), 0, 0, bm_image.Width, bm_image.Height, GraphicsUnit.Pixel, ia);
                g.Dispose();
                ia.Dispose();
                pictureBox1.Image = bm;
            }
            if (RB_blackwhite.Checked)
            {
                for (int x = 0; x < bm_image.Width; x++)
                {
                    
                    for (int y = 0; y < bm_image.Height; y++)
                    {
                        //get the pixel from the original image
                        Color originalColor = bm_image.GetPixel(x, y);
                        //create the grayscale version of the pixel
                        int newg = (int)((originalColor.A * .3) + (originalColor.G * .59) 
                            + (originalColor.B * .11));

                        Color newColor = Color.FromArgb(newg, newg, newg);
                        
                        bm_image.SetPixel(x, y, newColor);
                    }
                }
                pictureBox1.Image = bm_image;
            }
            if (RB_tint.Checked)
            {
            }
            if (RB_noise.Checked)
            {   
            }
        }
    }
}

tools I'm using:
*4 RadioButton(contrast, black&white, Tint, Noise).
*2 buttons (Load Picture and Transform(the Transform button will start an image manipulation based on the current settings.)
*Trackbar - will control the extent, and its interpretation is effect dependent.