【转】c#数字图像处理（四）线性点运算

迈不过友情╰ 2023-01-23 05:58 153阅读 0赞

转自：[https://www.cnblogs.com/dearzhoubi/p/8622325.html][https_www.cnblogs.com_dearzhoubi_p_8622325.html]

灰度图像的点运算可分为线性点运算和非线性点运算两种。  
4.1线性点运算定义  
线性点运算就是输出灰度级与输入灰度级呈线性关系的点运算。在这种情况下,灰度变换函数的形式为:

g(x, y)=pf(x,y)+L

其中 f(x,y) 为输入图像在点 (x,y) 的灰度值, g(x,y) 为相应的输出点的灰度值。显然,如果P=1和L=0,g(x,y)就是f(x,y)的复制;如果P<1,输出图像的对比度将增大;如果P>1,则对比度将减少;如果P=1而L≠0,该操作仅使所有像素的灰度值上移或下移,其效果是使整个图像在显示时更暗或更亮;如果P为负值,暗区域将变亮,亮区域将变暗,该操作完成了图像求补。

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linearPOForm.cs

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

Form1.cs

![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 Form1 : Form
        {
            public Form1()
            {
                InitializeComponent();
            }
    
            //文件名
            private string curFileName;
            //图像对象
            private System.Drawing.Bitmap curBitmpap;
    
            /// <summary>
            /// 打开图像文件
            /// </summary>
            private void open_Click(object sender, EventArgs e)
            {
                //创建OpenFileDialog
                OpenFileDialog opnDlg = new OpenFileDialog();
                //为图像选择一个筛选器
                opnDlg.Filter = "所有图像文件|*.bmp;*.pcx;*.png;*.jpg;*.gif;" +
                    "*.tif;*.ico;*.dxf;*.cgm;*.cdr;*.wmf;*.eps;*.emf|" +
                    "位图(*.bmp;*.jpg;*.png;...)|*.bmp;*.pcx;*.png;*.jpg;*.gif;*.tif;*.ico|" +
                    "矢量图(*.wmf;*.eps;*.emf;...)|*.dxf;*.cgm;*.cdr;*.wmf;*.eps;*.emf";
                //设置对话框标题
                opnDlg.Title = "打开图像文件";
                //启用“帮助”按钮
                opnDlg.ShowHelp = true;
    
                //如果结果为“打开”，选定文件
                if (opnDlg.ShowDialog() == DialogResult.OK)
                {
                    //读取当前选中的文件名
                    curFileName = opnDlg.FileName;
                    //使用Image.FromFile创建图像对象
                    try
                    {
                        curBitmpap = (Bitmap)Image.FromFile(curFileName);
                    }
                    catch (Exception exp)
                    {
                        MessageBox.Show(exp.Message);
                    }
                }
                //对窗体进行重新绘制，这将强制执行paint事件处理程序
                Invalidate();
            }
    
            /// <summary>
            /// 在控件需要重新绘制时发生
            /// </summary>
            private void Form1_Paint(object sender, PaintEventArgs e)
            {
                //获取Graphics对象
                Graphics g = e.Graphics;
                if (curBitmpap != null)
                {
                    //使用DrawImage方法绘制图像
                    //160,20：显示在主窗体内，图像左上角的坐标
                    //curBitmpap.Width, curBitmpap.Height图像的宽度和高度
                    g.DrawImage(curBitmpap, 160, 20, curBitmpap.Width, curBitmpap.Height);
                }
            }
    
            /// <summary>
            /// 关闭窗体 
            /// </summary>
            private void close_Click(object sender, EventArgs e)
            {
                this.Close();
            }
    
            private void histogram_Click(object sender, EventArgs e)
            {
                if (curBitmpap != null)
                {
                    //定义并实例化新窗体，并把图像数据传递给它
                    histForm histoGram = new histForm(curBitmpap);
                    histoGram.ShowDialog();
                }
            }
    
            private void linearPO_Click(object sender, EventArgs e)
            {
                if (curBitmpap!=null)
                {
                    //实例化linearPOForm窗体
                    linearPOForm linearForm = new linearPOForm();
    
                    //点击确定按钮
                    if (linearForm.ShowDialog()==DialogResult.OK)
                    {
                        Rectangle rect = new Rectangle(0, 0, curBitmpap.Width, curBitmpap.Height);
                        System.Drawing.Imaging.BitmapData bmpData = curBitmpap.LockBits(rect, 
                            System.Drawing.Imaging.ImageLockMode.ReadWrite, curBitmpap.PixelFormat);
                        IntPtr ptr = bmpData.Scan0;
                        int bytes = curBitmpap.Width * curBitmpap.Height;
                        byte[] grayValues = new byte[bytes];
                        System.Runtime.InteropServices.Marshal.Copy(ptr, grayValues, 0, bytes);
    
                        int temp = 0;
                        //得到斜率
                        double a = Convert.ToDouble(linearForm.GetScaling);
                        //得到偏移量
                        double b = Convert.ToDouble(linearForm.GetOffset);
    
                        for (int i = 0; i < bytes; i++)
                        {
                            //根据公式计算线性点运算
                            //加0.5表示四舍五入
                            temp = (int)(a * grayValues[i] + b + 0.5);
    
                            //灰度值限制在0~255之间
                            //大于255，则为255；小于0则为0
                            if (temp>255)
                            {
                                grayValues[i] = 255;
                            }
                            else if (temp<0)
                            {
                                grayValues[i] = 0;
                            }
                            else
                            {
                                grayValues[i] = (byte)temp;
                            }
                        }
                        System.Runtime.InteropServices.Marshal.Copy(grayValues, 0, ptr, bytes);
                        curBitmpap.UnlockBits(bmpData);
                    }
                    Invalidate();
                }
            }
        }
    }

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

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[https_www.cnblogs.com_dearzhoubi_p_8622325.html]: https://www.cnblogs.com/dearzhoubi/p/8622325.html
[c605d5094e44ea2edf5d0977e86f15bc.png]: /images/20221004/af7a144bc8de498fbb630c61740d9d72.png
[20e9d9a8ec1a64740b585eba0e736cb2.png]: /images/20221004/b5de68c0469c465dbaccd504cfe22380.png
[48304ba5e6f9fe08f3fa1abda7d326ab.png]: /images/20221004/ed2470d7236445cebcc44bdf702b6fc6.png
[06a7c4ed8689164330ba16a93dfd010f.png]: /images/20221004/0244a200127d42e2883aee71f4706dc5.png
[adf99aa24cf096d50bf8345e2f972244.png]: /images/20221004/632796c6571445faa17d315b1053d2b1.png
[e5e86b90fd25187883eb8f4cdbb8885a.png]: /images/20221004/c31cbd4243cb4ec78983a4529ce2ad02.png
[f4890cbad1aa046ff633ecb211551ce1.png]: /images/20221004/20d6f999703644d89399b0c6a6aff0f0.png