4. 灰階影像直方圖

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Windows.Forms.DataVisualization.Charting;

namespace Q4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void 結束離開ExitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Close();
        }

        private void 開啟彩色影像檔ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            openFileDialog1.ShowDialog();
            pictureBox1.Image = Bitmap.FromFile(openFileDialog1.FileName);
        }

        private void 彩色影像轉灰階影像ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            var bm = new Bitmap(pictureBox1.Image);
            pictureBox2.Image = bm;
            for (int x = 0; x < bm.Width; x++)
                for (int y = 0; y < bm.Height; y++)
                {
                    var p = bm.GetPixel(x, y);
                    var d = (int)(p.R * 0.3 + p.G * 0.59 + p.B * 0.11);
                    bm.SetPixel(x, y, Color.FromArgb(d, d, d));
                }
            pictureBox2.Image = bm;
        }

        Dictionary<int, int> k;
        private void 劃出ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            k = new Dictionary<int, int>();
            for (int i = 0; i < 256; i++) k[i] = 0;
            var bm = (Bitmap)pictureBox2.Image;
            for (int x = 0; x < bm.Width; x++)
            {
                for (global::System.Int32 y = 0; y < bm.Height; y++)
                {
                    var g = bm.GetPixel(x, y).R;
                    k[g]++;
                }
            }
            var series = chart1.Series.First();
            series.Points.Clear();
            foreach (var item in k)
            {
                series.Points.AddXY(item.Key, item.Value);
            }
        }

        private void 求最小灰階及最大灰階ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            int min = int.MaxValue;
            int max = int.MinValue;
            foreach (var item in k)
            {
                if (item.Value == 0) continue;

                if (item.Key > max) max = item.Key;
                if (item.Key < min) min = item.Key;
            }
            textBox1.Text = min.ToString();
            textBox2.Text = max.ToString();
        }

        private void 求出現最多之灰階及機率ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            int max = int.MinValue;
            int r = 0;
            foreach (var item in k)
            {
                if (item.Value > max)
                {
                    r = item.Key;
                    max = item.Value;
                }
            }
            textBox4.Text = r.ToString();
            textBox3.Text = ((double)max / (pictureBox2.Image.Width * pictureBox2.Image.Height)).ToString();
        }
    }
}