【转】c#数字图像处理（三）灰度直方图

深碍√TFBOYSˉ_ 2023-01-23 05:58 29阅读 0赞

转自：[https://www.cnblogs.com/dearzhoubi/p/8621804.html][https_www.cnblogs.com_dearzhoubi_p_8621804.html]

灰度直方图是灰度的函数,描述的是图像中具有该灰度级的像素的个数。如果用直角坐标系来表示,则它的横坐标是灰度级,纵坐标是该灰度出现的概率(像素的个数)。

![0f9a1e56d3cc136e05cc0ca2d9d31177.png][]

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Windows.Forms;
    
    namespace histogram
    {
        public partial class histForm : Form
        {
            //利用构造函数实现窗体之间的数据传递
            public histForm(Bitmap bmp)
            {
                InitializeComponent();
    
                //把主窗体的图像数据传递给从窗体
                bmpHist = bmp;
                //灰度级计数
                countPixel = new int[256];  //8位可表示256个灰度级
            }
    
            private void close_Click(object sender, EventArgs e)
            {
                this.Close();
            }
    
            //图像数据
            private System.Drawing.Bitmap bmpHist;
            //灰度等级
            private int[] countPixel;
            //记录最大的灰度级个数
            private int maxPixel;
    
    
            /// <summary>
            /// 计算各个灰度级所具有的像素个数
            /// </summary>
            private void histForm_Load(object sender, EventArgs e)
            {
                //锁定8位灰度位图
                Rectangle rect = new Rectangle(0, 0, bmpHist.Width, bmpHist.Height);
                System.Drawing.Imaging.BitmapData bmpData = bmpHist.LockBits(rect,
                    System.Drawing.Imaging.ImageLockMode.ReadWrite, bmpHist.PixelFormat);
                IntPtr ptr = bmpData.Scan0;
                int bytes = bmpHist.Width * bmpHist.Height;
                byte[] grayValues = new byte[bytes];
                System.Runtime.InteropServices.Marshal.Copy(ptr, grayValues, 0, bytes);//灰度值数据存入grayValues中
    
                byte temp = 0;
                maxPixel = 0;
                //灰度等级数组清零
                Array.Clear(countPixel, 0, 256);
                //计算各个灰度级的像素个数
                for (int i = 0; i < bytes; i++)
                {
                    //灰度级
                    temp = grayValues[i];
                    //计数加1
                    countPixel[temp]++;
                    if (countPixel[temp] > maxPixel)
                    {
                        //找到灰度频率最大的像素数，用于绘制直方图
                        maxPixel = countPixel[temp];
                    }
                }
    
                //解锁
                System.Runtime.InteropServices.Marshal.Copy(grayValues, 0, ptr, bytes);
                bmpHist.UnlockBits(bmpData);
            }
    
    
            /// <summary>
            /// 绘制直方图
            /// </summary>
            private void histForm_Paint(object sender, PaintEventArgs e)
            {
                //获取Graphics对象
                Graphics g = e.Graphics;
    
                //创建一个宽度为1的黑色钢笔
                Pen curPen = new Pen(Brushes.Black, 1);
    
                //绘制坐标轴
                g.DrawLine(curPen, 50, 240, 320, 240);//横坐标
                g.DrawLine(curPen, 50, 240, 50, 30);//纵坐标
    
                //绘制并标识坐标刻度
                g.DrawLine(curPen, 100, 240, 100, 242);
                g.DrawLine(curPen, 150, 240, 150, 242);
                g.DrawLine(curPen, 200, 240, 200, 242);
                g.DrawLine(curPen, 250, 240, 250, 242);
                g.DrawLine(curPen, 300, 240, 300, 242);
                g.DrawString("0", new Font("New Timer", 8), Brushes.Black, new PointF(46, 242));
                g.DrawString("50", new Font("New Timer", 8), Brushes.Black, new PointF(92,242));
                g.DrawString("100", new Font("New Timer", 8), Brushes.Black, new PointF(139, 242));
                g.DrawString("150", new Font("New Timer", 8), Brushes.Black, new PointF(189, 242));
                g.DrawString("200", new Font("New Timer", 8), Brushes.Black, new PointF(239, 242));
                g.DrawString("250", new Font("New Timer", 8), Brushes.Black, new PointF(289, 242));
                g.DrawLine(curPen, 48, 40, 50, 40);
                g.DrawString("0", new Font("New Timer", 8), Brushes.Black, new PointF(34, 234));
                g.DrawString(maxPixel.ToString(), new Font("New Timer", 8), Brushes.Black, new PointF(18, 34));
    
                //绘制直方图
                double temp = 0;
                for (int i = 0; i < 256; i++)
                {
                    //纵坐标长度
                    temp = 200.0 * countPixel[i] / maxPixel;
                    g.DrawLine(curPen, 50 + i, 240, 50 + i, 240 - (int)temp);
                }
                //释放对象
                curPen.Dispose();
            }
        }
    }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

![f403f4284c33688bde95076494432cc6.png][]

[https_www.cnblogs.com_dearzhoubi_p_8621804.html]: https://www.cnblogs.com/dearzhoubi/p/8621804.html
[0f9a1e56d3cc136e05cc0ca2d9d31177.png]: /images/20221004/2f8125212f9147a5af626d4d8bbd931a.png
[48304ba5e6f9fe08f3fa1abda7d326ab.png]: /images/20221004/dc9a75321c3a4f67ab73ed4ac73aa590.png
[f403f4284c33688bde95076494432cc6.png]: /images/20221004/b3d632dc6b4b4f63a6b0610f04f55969.png