C# 图像处理之灰度（去颜色的三种方法）

【实例截图】

【核心代码】

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.Diagnostics;

namespace ImageProcessing
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Stopwatch sw = new Stopwatch();
        Bitmap bitmap;
        Bitmap newbitmap;

        private void button1_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                string path = openFileDialog1.FileName;
                bitmap = (Bitmap)Image.FromFile(path);
                pictureBox1.Image = bitmap.Clone() as Image;
            }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                sw.Reset();
                sw.Start();
                Color pixel;
                int ret;
                for (int x = 0; x < newbitmap.Width; x  )
                {
                    for (int y = 0; y < newbitmap.Height; y  )
                    {
                        pixel = newbitmap.GetPixel(x, y);
                        ret = (int)(pixel.R * 0.299   pixel.G * 0.587   pixel.B * 0.114);
                        newbitmap.SetPixel(x, y, Color.FromArgb(ret, ret, ret));
                    }
                }
                sw.Stop();
                label1.Text = sw.ElapsedMilliseconds.ToString();
                pictureBox2.Image = newbitmap.Clone() as Image;
            }
        }

        private void button5_Click(object sender, EventArgs e)
        {
            if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                sw.Reset();
                sw.Start();
                Rectangle rect = new Rectangle(0, 0, newbitmap.Width, newbitmap.Height);
                System.Drawing.Imaging.BitmapData bmpdata = newbitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, newbitmap.PixelFormat);
                IntPtr ptr = bmpdata.Scan0;

                int bytes = newbitmap.Width * newbitmap.Height * 3;
                byte[] rgbvalues = new byte[bytes];

                System.Runtime.InteropServices.Marshal.Copy(ptr, rgbvalues, 0, bytes);

                double colortemp = 0;
                for (int i = 0; i < rgbvalues.Length; i  = 3)
                {
                    colortemp = rgbvalues[i   2] * 0.299   rgbvalues[i   1] * 0.587   rgbvalues[i] * 0.114;
                    rgbvalues[i] = rgbvalues[i   1] = rgbvalues[i   2] = (byte)colortemp;
                }

                System.Runtime.InteropServices.Marshal.Copy(rgbvalues, 0, ptr, bytes);

                newbitmap.UnlockBits(bmpdata);
                sw.Stop();
                label2.Text = sw.ElapsedMilliseconds.ToString();
                pictureBox2.Image = newbitmap.Clone() as Image;
            }
        }

        private void button6_Click(object sender, EventArgs e)
        {
            if (bitmap != null)
            {
                newbitmap = bitmap.Clone() as Bitmap;
                sw.Reset();
                sw.Start();
                Rectangle rect = new Rectangle(0, 0, newbitmap.Width, newbitmap.Height);
                System.Drawing.Imaging.BitmapData bmpdata = newbitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, newbitmap.PixelFormat);

                byte temp;

                unsafe
                {
                    byte* ptr = (byte*)(bmpdata.Scan0);

                    for (int x = 0; x < bmpdata.Width; x  )
                    {
                        for (int y = 0; y < bmpdata.Height; y  )
                        {
                            temp = (byte)(0.299 * ptr[2]   0.587 * ptr[1]   0.114 * ptr[0]);
                            ptr[0] = ptr[1] = ptr[2] = temp;
                            ptr  = 3;
                        }
                        ptr  = bmpdata.Stride - bmpdata.Width * 3;
                    }
                }

                newbitmap.UnlockBits(bmpdata);
                sw.Stop();
                label3.Text = sw.ElapsedMilliseconds.ToString();
                pictureBox2.Image = newbitmap.Clone() as Image;
            }
        }

    }
}