C#图像处理
（各种旋转、改变大小、柔化、锐化、雾化、底片、浮雕、黑白、滤镜效果）
一、各种旋转、改变大小
注意：先要添加画图相关的using引用。
//向右旋转图像90°代码如下:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");//加载图像g.FillRectangle(Brushes.White, this.ClientRectangle);//填充窗体背景为白色Point[] destinationPoints = {new Point(100, 0), // destination for upper-left point of originalnew Point(100, 100),// destination for upper-right point of originalnew Point(0, 0)}; // destination for lower-left point of originalg.DrawImage(bmp, destinationPoints);
}
//旋转图像180°代码如下:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");g.FillRectangle(Brushes.White, this.ClientRectangle);Point[] destinationPoints = {new Point(0, 100), // destination for upper-left point of originalnew Point(100, 100),// destination for upper-right point of originalnew Point(0, 0)}; // destination for lower-left point of originalg.DrawImage(bmp, destinationPoints);
}
//图像切变代码:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");g.FillRectangle(Brushes.White, this.ClientRectangle);Point[] destinationPoints = {new Point(0, 0), // destination for upper-left point of originalnew Point(100, 0), // destination for upper-right point of originalnew Point(50, 100)};// destination for lower-left point of originalg.DrawImage(bmp, destinationPoints);
}
//图像截取:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");g.FillRectangle(Brushes.White, this.ClientRectangle);Rectangle sr = new Rectangle(80, 60, 400, 400);//要截取的矩形区域Rectangle dr = new Rectangle(0, 0, 200, 200);//要显示到Form的矩形区域g.DrawImage(bmp, dr, sr, GraphicsUnit.Pixel);
}
//改变图像大小:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");g.FillRectangle(Brushes.White, this.ClientRectangle);int width = bmp.Width;int height = bmp.Height;// 改变图像大小使用低质量的模式g.InterpolationMode = InterpolationMode.NearestNeighbor;g.DrawImage(bmp, new Rectangle(10, 10, 120, 120), // source rectangle
new Rectangle(0, 0, width, height), // destination rectangleGraphicsUnit.Pixel);// 使用高质量模式//g.CompositingQuality = CompositingQuality.HighSpeed;g.InterpolationMode = InterpolationMode.HighQualityBicubic;g.DrawImage(bmp,new Rectangle(130, 10, 120, 120), new Rectangle(0, 0, width, height),GraphicsUnit.Pixel);
}
//设置图像的分辩率:private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Bitmap bmp = new Bitmap("rama.jpg");g.FillRectangle(Brushes.White, this.ClientRectangle);bmp.SetResolution(300f, 300f);g.DrawImage(bmp, 0, 0);bmp.SetResolution(1200f, 1200f);g.DrawImage(bmp, 180, 0);
}
//用GDI+画图private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics gForm = e.Graphics;gForm.FillRectangle(Brushes.White, this.ClientRectangle);for (int i = 1; i <= 7; ++i){
//在窗体上面画出橙色的矩形
Rectangle r = new Rectangle(i*40-15, 0, 15,this.ClientRectangle.Height);gForm.FillRectangle(Brushes.Orange, r);
}
//在内存中创建一个Bitmap并设置CompositingModeBitmap bmp = new Bitmap(260, 260,
System.Drawing.Imaging.PixelFormat.Format32bppArgb);Graphics gBmp = Graphics.FromImage(bmp);gBmp.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;// 创建一个带有Alpha的红色区域// 并将其画在内存的位图里面Color red = Color.FromArgb(0x60, 0xff, 0, 0);Brush redBrush = new SolidBrush(red);gBmp.FillEllipse(redBrush, 70, 70, 160, 160);// 创建一个带有Alpha的绿色区域Color green = Color.FromArgb(0x40, 0, 0xff, 0);Brush greenBrush = new SolidBrush(green);gBmp.FillRectangle(greenBrush, 10, 10, 140, 140);//在窗体上面画出位图 now draw the bitmap on our windowgForm.DrawImage(bmp, 20, 20, bmp.Width, bmp.Height);// 清理资源bmp.Dispose();gBmp.Dispose();redBrush.Dispose();greenBrush.Dispose();
}
//在窗体上面绘图并显示图像private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e){
Graphics g = e.Graphics;Pen blackPen = new Pen(Color.Black, 1);
if (ClientRectangle.Height / 10 > 0)
{
for (int y = 0; y < ClientRectangle.Height; y += ClientRectangle.Height / 10)
{
g.DrawLine(blackPen, new Point(0, 0), new Point(ClientRectangle.Width, y));
}
}
blackPen.Dispose();
}
C# 使用Bitmap类进行图片裁剪
在Mapwin（手机游戏地图编辑器）生成的地图txt文件中添加自己需要处理的数据后转换成可在手机（Ophone）开发环境中使用的字节流地图文件的小工具，其中就涉及到图片的裁剪和生成了。有以下几种方式。
方法一：拷贝像素。
当然这种方法是最笨的，效率也就低了些。
在Bitmap类中我们可以看到这样两个方法：GetPixel（int x, int y）和SetPixel（int x, int y, Color color）方法。从字面的含以上就知道前者是获取图像某点像素值，是用Color对象返回的；后者是将已知像素描画到制定的位置。
下面就来做个实例检验下：
1.首先创建一个Windows Form窗体程序，往该窗体上拖放7个PictureBox控件，第一个用于放置并显示原始的大图片，其后6个用于放置并显示裁剪后新生成的6个小图；
2.放置原始大图的PictureBox控件name属性命名为pictureBoxBmpRes，其后pictureBox1到pictureBox6依次命名，并放置在合适的位置；
3.双击Form窗体，然后在Form1_Load事件中加入下面的代码即可。
//导入图像资源
Bitmap bmpRes = null;
String strPath = Application.ExecutablePath;
try{
int nEndIndex = strPath.LastIndexOf('//');
strPath = strPath.Substring(0,nEndIndex) + "//Bmp//BmpResMM.bmp";
bmpRes = new Bitmap(strPath);
//窗体上显示加载图片
pictureBoxBmpRes.Width = bmpRes.Width;
pictureBoxBmpRes.Height = bmpRes.Height;
pictureBoxBmpRes.Image = bmpRes;
}
catch(Exception ex)
{
System.Windows.Forms.MessageBox.Show("图片资源加载失败！/r/n" + ex.ToString());
}
//裁剪图片(裁成2行3列的6张图片)
int nYClipNum = 2, nXClipNum = 3;
Bitmap[] bmpaClipBmpArr = new Bitmap[nYClipNum * nXClipNum];
for (int nYClipNumIndex = 0; nYClipNumIndex < nYClipNum; nYClipNumIndex++)
{
for (int nXClipNumIndex = 0; nXClipNumIndex < nXClipNum; nXClipNumIndex++)
{
int nClipWidth = bmpRes.Width / nXClipNum;
int nClipHight = bmpRes.Height / nYClipNum;
int nBmpIndex = nXClipNumIndex + nYClipNumIndex * nYClipNum + (nYClipNumIndex > 0?1:0);
bmpaClipBmpArr[nBmpIndex] = new Bitmap(nClipWidth, nClipHight);
for(int nY = 0; nY < nClipHight; nY++)
{
for(int nX = 0; nX < nClipWidth; nX++)
{
int nClipX = nX + nClipWidth * nXClipNumIndex;
int nClipY = nY + nClipHight * nYClipNumIndex;
Color cClipPixel = bmpRes.GetPixel(nClipX, nClipY);
bmpaClipBmpArr[nBmpIndex].SetPixel(nX, nY, cClipPixel);
}
}
}
}
PictureBox[] picbShow = new PictureBox[nYClipNum * nXClipNum];
picbShow[0] = pictureBox1;
picbShow[1] = pictureBox2;
picbShow[2] = pictureBox3;
picbShow[3] = pictureBox4;
picbShow[4] = pictureBox5;
picbShow[5] = pictureBox6;
for (int nLoop = 0; nLoop < nYClipNum * nXClipNum; nLoop++)
{
picbShow[nLoop].Width = bmpRes.Width / nXClipNum;
picbShow[nLoop].Height = bmpRes.Height / nYClipNum;
picbShow[nLoop].Image = bmpaClipBmpArr[nLoop];
}
现在看看那些地方需要注意的了。其中
int nBmpIndex =
nXClipNumIndex + nYClipNumIndex * nYClipNum + (nYClipNumIndex > 0?1:0);
这句定义了存储裁剪图片对象在数组中的索引，需要注意的就是后面的(nYClipNumIndex > 0?1:0)——因为只有当裁剪的对象处于第一行以外的行时需要将索引加1；
另外，因为这种方法的效率不高，程序运行起来还是顿了下。如果有兴趣的话，可以将以上的代码放到一个按钮Click事件函数中，当单击该按钮时就可以感觉到了。
方法二：运用Clone函数局部复制。
同样在Bitmap中可以找到Clone（）方法，该方法有三个重载方法。Clone（），Clone（Rectangle， PixelFormat）和Clone（RectangleF， PixelFormat）。第一个方法将创建并返回一个精确的实例对象，后两个就是我们这里需要用的局部裁剪了（其实后两个方法本人觉得用法上差不多）。
将上面的程序稍稍改进下——将裁剪的处理放到一个按钮事件函数中，然后再托一个按钮好窗体上，最后将下面的代码复制到该按钮的事件函数中。
for (int nYClipNumIndex = 0; nYClipNumIndex < nYClipNum; nYClipNumIndex++)
{
for (int nXClipNumIndex = 0; nXClipNumIndex < nXClipNum; nXClipNumIndex++)
{
int nClipWidth = bmpRes.Width / nXClipNum;
int nClipHight = bmpRes.Height / nYClipNum;
int nBmpIndex =
nXClipNumIndex + nYClipNumIndex * nYClipNum + (nYClipNumIndex > 0 ? 1 : 0);
Rectangle rClipRect = new Rectangle(nClipWidth * nXClipNumIndex,
nClipHight * nYClipNumIndex,
nClipWidth,
nClipHight);
bmpaClipBmpArr[nBmpIndex] = bmpRes.Clone(rClipRect, bmpRes.PixelFormat);
}
}
运行程序，单击按钮检验下，发现速度明显快可很多。
其实这种方法较第一中方法不同的地方仅只是变换了for循环中的拷贝部分的处理，
Rectangle rClipRect = new Rectangle(nClipWidth * nXClipNumIndex,
nClipHight * nYClipNumIndex,
nClipWidth,
nClipHight);
bmpaClipBmpArr[nBmpIndex] = bmpRes.Clone(rClipRect, bmpRes.PixelFormat);
一. 底片效果原理: GetPixel方法获得每一点像素的值, 然后再使用SetPixel方法将取反后的颜色值设置到对应的点.效果图:
代码实现:
private void button1_Click(object sender, EventArgs e) { //以底片效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap newbitmap = new Bitmap(Width, Height); Bitmap oldbitmap = (Bitmap)this.pictureBox1.Image; Color pixel; for (int x = 1; x < Width; x++) { for (int y = 1; y < Height; y++) { int r, g, b; pixel = oldbitmap.GetPixel(x, y); r = 255 - pixel.R; g = 255 - pixel.G; b = 255 - pixel.B; newbitmap.SetPixel(x, y, Color.FromArgb(r, g, b)); } } this.pictureBox1.Image = newbitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information); } }
二. 浮雕效果
原理: 对图像像素点的像素值分别与相邻像素点的像素值相减后加上128, 然后将其作为新的像素点的值.
效果图:
代码实现:
浮雕效果 private void button1_Click(object sender, EventArgs e) { //以浮雕效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap newBitmap = new Bitmap(Width, Height); Bitmap oldBitmap = (Bitmap)this.pictureBox1.Image; Color pixel1, pixel2; for (int x = 0; x < Width - 1; x++) { for (int y = 0; y < Height - 1; y++) { int r = 0, g = 0, b = 0; pixel1 = oldBitmap.GetPixel(x, y); pixel2 = oldBitmap.GetPixel(x + 1, y + 1); r = Math.Abs(pixel1.R - pixel2.R + 128); g = Math.Abs(pixel1.G - pixel2.G + 128); b = Math.Abs(pixel1.B - pixel2.B + 128); if (r > 255) r = 255; if (r < 0) r = 0; if (g > 255) g = 255; if (g < 0) g = 0; if (b > 255) b = 255; if (b < 0) b = 0; newBitmap.SetPixel(x, y, Color.FromArgb(r, g, b)); } } this.pictureBox1.Image = newBitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information); } }
三. 黑白效果
原理: 彩色图像处理成黑白效果通常有3种算法；
(1).最大值法: 使每个像素点的 R, G, B 值等于原像素点的 RGB (颜色值) 中最大的一个；
(2).平均值法: 使用每个像素点的 R,G,B值等于原像素点的RGB值的平均值；
(3).加权平均值法: 对每个像素点的 R, G, B值进行加权
---自认为第三种方法做出来的黑白效果图像最 "真实".
效果图:
代码实现:
黑白效果 private void button1_Click(object sender, EventArgs e) { //以黑白效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap newBitmap = new Bitmap(Width, Height); Bitmap oldBitmap = (Bitmap)this.pictureBox1.Image; Color pixel; for (int x = 0; x < Width; x++) for (int y = 0; y < Height; y++) { pixel = oldBitmap.GetPixel(x, y); int r, g, b, Result = 0; r = pixel.R; g = pixel.G; b = pixel.B; //实例程序以加权平均值法产生黑白图像 int iType =2; switch (iType) { case 0://平均值法 Result = ((r + g + b) / 3); break; case 1://最大值法 Result = r > g ? r : g; Result = Result > b ? Result : b; break; case 2://加权平均值法 Result = ((int)(0.7 * r) + (int)(0.2 * g) + (int)(0.1 * b)); break; } newBitmap.SetPixel(x, y, Color.FromArgb(Result, Result, Result)); } this.pictureBox1.Image = newBitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示"); } }
四. 柔化效果
原理: 当前像素点与周围像素点的颜色差距较大时取其平均值.
效果图:
代码实现:
柔化效果 private void button1_Click(object sender, EventArgs e) { //以柔化效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap bitmap = new Bitmap(Width, Height); Bitmap MyBitmap = (Bitmap)this.pictureBox1.Image; Color pixel; //高斯模板 int[] Gauss ={ 1, 2, 1, 2, 4, 2, 1, 2, 1 }; for (int x = 1; x < Width - 1; x++) for (int y = 1; y < Height - 1; y++) { int r = 0, g = 0, b = 0; int Index = 0; for (int col = -1; col <= 1; col++) for (int row = -1; row <= 1; row++) { pixel = MyBitmap.GetPixel(x + row, y + col); r += pixel.R * Gauss[Index]; g += pixel.G * Gauss[Index]; b += pixel.B * Gauss[Index]; Index++; } r /= 16; g /= 16; b /= 16; //处理颜色值溢出 r = r > 255 ? 255 : r; r = r < 0 ? 0 : r; g = g > 255 ? 255 : g; g = g < 0 ? 0 : g; b = b > 255 ? 255 : b; b = b < 0 ? 0 : b; bitmap.SetPixel(x - 1, y - 1, Color.FromArgb(r, g, b)); } this.pictureBox1.Image = bitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示"); } }
五.锐化效果
原理:突出显示颜色值大(即形成形体边缘)的像素点.
效果图:
实现代码:
锐化效果 private void button1_Click(object sender, EventArgs e) { //以锐化效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap newBitmap = new Bitmap(Width, Height); Bitmap oldBitmap = (Bitmap)this.pictureBox1.Image; Color pixel; //拉普拉斯模板 int[] Laplacian ={ -1, -1, -1, -1, 9, -1, -1, -1, -1 }; for (int x = 1; x < Width - 1; x++) for (int y = 1; y < Height - 1; y++) { int r = 0, g = 0, b = 0; int Index = 0; for (int col = -1; col <= 1; col++) for (int row = -1; row <= 1; row++) { pixel = oldBitmap.GetPixel(x + row, y + col); r += pixel.R * Laplacian[Index]; g += pixel.G * Laplacian[Index]; b += pixel.B * Laplacian[Index]; Index++; } //处理颜色值溢出 r = r > 255 ? 255 : r; r = r < 0 ? 0 : r; g = g > 255 ? 255 : g; g = g < 0 ? 0 : g; b = b > 255 ? 255 : b; b = b < 0 ? 0 : b; newBitmap.SetPixel(x - 1, y - 1, Color.FromArgb(r, g, b)); } this.pictureBox1.Image = newBitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示"); } }
六. 雾化效果
原理: 在图像中引入一定的随机值, 打乱图像中的像素值
效果图:
实现代码:
雾化效果 private void button1_Click(object sender, EventArgs e) { //以雾化效果显示图像 try { int Height = this.pictureBox1.Image.Height; int Width = this.pictureBox1.Image.Width; Bitmap newBitmap = new Bitmap(Width, Height); Bitmap oldBitmap = (Bitmap)this.pictureBox1.Image; Color pixel; for (int x = 1; x < Width - 1; x++) for (int y = 1; y < Height - 1; y++) { System.Random MyRandom = new Random(); int k = MyRandom.Next(123456); //像素块大小 int dx = x + k % 19; int dy = y + k % 19; if (dx >= Width) dx = Width - 1; if (dy >= Height) dy = Height - 1; pixel = oldBitmap.GetPixel(dx, dy); newBitmap.SetPixel(x, y, pixel); } this.pictureBox1.Image = newBitmap; } catch (Exception ex) { MessageBox.Show(ex.Message, "信息提示"); } }
浅谈Visual C#进行图像处理
作者：彭军 http://pengjun.org.cn
这里之所以说“浅谈”是因为我这里只是简单的介绍如何使用Visual C#进行图像的读入、保存以及对像素的访问。而不涉及太多的算法。
一、读入图像
在Visual C#中我们可以使用一个Picture Box控件来显示图片，如下： private void btnOpenImage_Click(object sender, EventArgs e) { OpenFileDialog ofd = new OpenFileDialog(); ofd.Filter = "BMP Files(*.bmp)|*.bmp|JPG Files(*.jpg;*.jpeg)|*.jpg;*.jpeg|All Files(*.*)|*.*"; ofd.CheckFileExists = true; ofd.CheckPathExists = true; if (ofd.ShowDialog() == DialogResult.OK) { //pbxShowImage.ImageLocation = ofd.FileName; bmp = new Bitmap(ofd.FileName); if (bmp==null) { MessageBox.Show("加载图片失败!", "错误"); return; } pbxShowImage.Image = bmp; ofd.Dispose(); } }其中bmp为类的一个对象：private Bitmap bmp=null;在使用Bitmap类和BitmapData类之前，需要使用using System.Drawing.Imaging;二、保存图像 private void btnSaveImage_Click(object sender, EventArgs e) { if (bmp == null) return;
SaveFileDialog sfd = new SaveFileDialog(); sfd.Filter = "BMP Files(*.bmp)|*.bmp|JPG Files(*.jpg;*.jpeg)|*.jpg;*.jpeg|All Files(*.*)|*.*"; if (sfd.ShowDialog() == DialogResult.OK) { pbxShowImage.Image.Save(sfd.FileName); MessageBox.Show("保存成功!","提示"); sfd.Dispose(); } }三、对像素的访问我们可以来建立一个GrayBitmapData类来做相关的处理。整个类的程序如下：using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Drawing;using System.Drawing.Imaging;using System.Windows.Forms;
namespace ImageElf{ class GrayBitmapData { public byte[,] Data;//保存像素矩阵 public int Width;//图像的宽度 public int Height;//图像的高度
public GrayBitmapData() { this.Width = 0; this.Height = 0; this.Data = null; }
public GrayBitmapData(Bitmap bmp) { BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); this.Width = bmpData.Width; this.Height = bmpData.Height; Data = new byte[Height, Width]; unsafe { byte* ptr = (byte*)bmpData.Scan0.ToPointer(); for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { //将24位的RGB彩色图转换为灰度图 int temp = (int)(0.114 * (*ptr++)) + (int)(0.587 * (*ptr++))+(int)(0.299 * (*ptr++)); Data[i, j] = (byte)temp; } ptr += bmpData.Stride - Width * 3;//指针加上填充的空白空间 } } bmp.UnlockBits(bmpData); }
public GrayBitmapData(string path) : this(new Bitmap(path)) { }
public Bitmap ToBitmap() { Bitmap bmp=new Bitmap(Width,Height,PixelFormat.Format24bppRgb); BitmapData bmpData=bmp.LockBits(new Rectangle(0,0,Width,Height),ImageLockMode.WriteOnly,PixelFormat.Format24bppRgb); unsafe { byte* ptr=(byte*)bmpData.Scan0.ToPointer(); for(int i=0;i<Height;i++) { for(int j=0;j<Width;j++) { *(ptr++)=Data[i,j]; *(ptr++)=Data[i,j]; *(ptr++)=Data[i,j]; } ptr+=bmpData.Stride-Width*3; } } bmp.UnlockBits(bmpData); return bmp; }
public void ShowImage(PictureBox pbx) { Bitmap b = this.ToBitmap(); pbx.Image = b; //b.Dispose(); }
public void SaveImage(string path) { Bitmap b=ToBitmap(); b.Save(path); //b.Dispose(); }//均值滤波 public void AverageFilter(int windowSize) { if (windowSize % 2 == 0) { return; }
for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { int sum = 0; for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++) { for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++) { int a = i + g, b = j + k; if (a < 0) a = 0; if (a > Height - 1) a = Height - 1; if (b < 0) b = 0; if (b > Width - 1) b = Width - 1; sum += Data[a, b]; } } Data[i,j]=(byte)(sum/(windowSize*windowSize)); } } }//中值滤波 public void MidFilter(int windowSize) { if (windowSize % 2 == 0) { return; }
int[] temp = new int[windowSize * windowSize]; byte[,] newdata = new byte[Height, Width]; for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { int n = 0; for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++) { for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++) { int a = i + g, b = j + k; if (a < 0) a = 0; if (a > Height - 1) a = Height - 1; if (b < 0) b = 0; if (b > Width - 1) b = Width - 1; temp[n++]= Data[a, b]; } } newdata[i, j] = GetMidValue(temp,windowSize*windowSize); } }
for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { Data[i, j] = newdata[i, j]; } } }//获得一个向量的中值 private byte GetMidValue(int[] t, int length) { int temp = 0; for (int i = 0; i < length - 2; i++) { for (int j = i + 1; j < length - 1; j++) { if (t[i] > t[j]) { temp = t[i]; t[i] = t[j]; t[j] = temp; } } }
return (byte)t[(length - 1) / 2]; }//一种新的滤波方法，是亮的更亮、暗的更暗 public void NewFilter(int windowSize) { if (windowSize % 2 == 0) { return; }
for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { int sum = 0; for (int g = -(windowSize - 1) / 2; g <= (windowSize - 1) / 2; g++) { for (int k = -(windowSize - 1) / 2; k <= (windowSize - 1) / 2; k++) { int a = i + g, b = j + k; if (a < 0) a = 0; if (a > Height - 1) a = Height - 1; if (b < 0) b = 0; if (b > Width - 1) b = Width - 1; sum += Data[a, b]; } } double avg = (sum+0.0) / (windowSize * windowSize); if (avg / 255 < 0.5) { Data[i, j] = (byte)(2 * avg / 255 * Data[i, j]); } else { Data[i,j]=(byte)((1-2*(1-avg/255.0)*(1-Data[i,j]/255.0))*255); } } } }//直方图均衡 public void HistEqual() { double[] num = new double[256] ; for(int i=0;i<256;i++) num[i]=0;
for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { num[Data[i, j]]++; } }
double[] newGray = new double[256]; double n = 0; for (int i = 0; i < 256; i++) { n += num[i]; newGray[i] = n * 255 / (Height * Width); }
for (int i = 0; i < Height; i++) { for (int j = 0; j < Width; j++) { Data[i,j]=(byte)newGray[Data[i,j]]; } } }
}}在GrayBitmapData类中，只要我们对一个二维数组Data进行一系列的操作就是对图片的操作处理。在窗口上，我们可以使用一个按钮来做各种调用：//均值滤波 private void btnAvgFilter_Click(object sender, EventArgs e) { if (bmp == null) return; GrayBitmapData gbmp = new GrayBitmapData(bmp); gbmp.AverageFilter(3); gbmp.ShowImage(pbxShowImage); }//转换为灰度图 private void btnToGray_Click(object sender, EventArgs e) { if (bmp == null) return; GrayBitmapData gbmp = new GrayBitmapData(bmp); gbmp.ShowImage(pbxShowImage); }
四、总结
在Visual c#中对图像进行处理或访问，需要先建立一个Bitmap对象，然后通过其LockBits方法来获得一个BitmapData类的对象，然后通过获得其像素数据的首地址来对Bitmap对象的像素数据进行操作。当然，一种简单但是速度慢的方法是用Bitmap类的GetPixel和SetPixel方法。其中BitmapData类的Stride属性为每行像素所占的字节。
C# colorMatrix 对图片的处理 : 亮度调整 抓屏 翻转 随鼠标画矩形
1.图片亮度处理
private void btn_Grap_Click(object sender, EventArgs e)
{
//亮度百分比
int percent = 50;
Single v = 0.006F * percent;
Single[][] matrix = {
new Single[] { 1, 0, 0, 0, 0 },
new Single[] { 0, 1, 0, 0, 0 },
new Single[] { 0, 0, 1, 0, 0 },
new Single[] { 0, 0, 0, 1, 0 },
new Single[] { v, v, v, 0, 1 }
};
System.Drawing.Imaging.ColorMatrix cm = new System.Drawing.Imaging.ColorMatrix(matrix);
System.Drawing.Imaging.ImageAttributes attr = new System.Drawing.Imaging.ImageAttributes();
attr.SetColorMatrix(cm);
//Image tmp
Image tmp = Image.FromFile("1.png");
this.pictureBox_Src.Image = Image.FromFile("1.png");
Graphics g = Graphics.FromImage(tmp);
try
{
Rectangle destRect = new Rectangle(0, 0, tmp.Width, tmp.Height);
g.DrawImage(tmp, destRect, 0, 0, tmp.Width, tmp.Height, GraphicsUnit.Pixel, attr);
}
finally
{
g.Dispose();
}
this.pictureBox_Dest.Image = (Image)tmp.Clone();
}
2.抓屏将生成的图片显示在pictureBox
private void btn_Screen_Click(object sender, EventArgs e)
{
Image myImage = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
Graphics g = Graphics.FromImage(myImage);
g.CopyFromScreen(new Point(0, 0), new Point(0, 0), new Size(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height));
//IntPtr dc1 = g.GetHdc(); //此处这两句多余，具体看最后GetHdc()定义
//g.ReleaseHdc(dc1);
g.Dispose();
this.pictureBox_Src.SizeMode = PictureBoxSizeMode.StretchImage;
this.pictureBox_Src.Image = myImage;
myImage.Save("Screen", ImageFormat.Png);
}
3.翻转
private void btn_RotateFlip_Click(object sender, EventArgs e)
{
this.pictureBox_Src.Image = Image.FromFile("1.png");
Image tmp = Image.FromFile("1.png");
tmp.RotateFlip(RotateFlipType.Rotate90FlipNone);
this.pictureBox_Dest.Image = tmp;
}
4.跟随鼠标在 pictureBox的图片上画矩形
private int intStartX = 0;
private int intStartY = 0;
private bool isMouseDraw = false;
private void pictureBox_Src_MouseDown(object sender, MouseEventArgs e)
{
isMouseDraw = true;
intStartX = e.X;
intStartY = e.Y;
}
private void pictureBox_Src_MouseMove(object sender, MouseEventArgs e)
{
if (isMouseDraw)
{
try
{
//Image tmp = Image.FromFile("1.png");
Graphics g = this.pictureBox_Src.CreateGraphics();
//清空上次画下的痕迹
g.Clear(this.pictureBox_Src.BackColor);
Brush brush = new SolidBrush(Color.Red);
Pen pen = new Pen(brush, 1);
pen.DashStyle = DashStyle.Solid;
g.DrawRectangle(pen, new Rectangle(intStartX > e.X ? e.X : intStartX, intStartY > e.Y ? e.Y : intStartY, Math.Abs(e.X - intStartX), Math.Abs(e.Y - intStartY)));
g.Dispose();
//this.pictureBox_Src.Image = tmp;
}
catch (Exception ex)
{
ex.ToString();
}
}
}
private void pictureBox_Src_MouseUp(object sender, MouseEventArgs e)
{
isMouseDraw = false;
intStartX = 0;
intStartY = 0;
}
5.取灰度
private void btn_GetGray_Click(object sender, EventArgs e)
{
this.pictureBox_Src.Image = Image.FromFile("1.png");
Bitmap currentBitmap = new Bitmap(this.pictureBox_Src.Image);
Graphics g = Graphics.FromImage(currentBitmap);
ImageAttributes ia = new ImageAttributes();
float[][] colorMatrix = {
new float[] {0.299f, 0.299f, 0.299f, 0, 0},
new float[] {0.587f, 0.587f, 0.587f, 0, 0},
new float[] {0.114f, 0.114f, 0.114f, 0, 0},
new float[] {0, 0, 0, 1, 0},
new float[] {0, 0, 0, 0, 1}
};
ColorMatrix cm = new ColorMatrix(colorMatrix);
ia.SetColorMatrix(cm, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
g.DrawImage(currentBitmap, new Rectangle(0, 0, currentBitmap.Width, currentBitmap.Height), 0, 0, currentBitmap.Width, currentBitmap.Height, GraphicsUnit.Pixel, ia);
this.pictureBox_Dest.Image = (Image)(currentBitmap.Clone());
g.Dispose();
}
Graphics.GetHdc 方法
.NET Framework 4
.NET Framework 3.5 .NET Framework 3.0 .NET Framework 2.0
获取与此 Graphics 关联的设备上下文的句柄。
命名空间： System.Drawing程序集： System.Drawing（在 System.Drawing.dll 中）
语法
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags =
SecurityPermissionFlag.UnmanagedCode)]
public IntPtr GetHdc()
返回值
类型：System.IntPtr与此 Graphics 关联的设备上下文的句柄。
实现
IDeviceContext.GetHdc()
备注
设备上下文是一个基于 GDI 的 Windows 结构，它定义一组图形对象及其关联的特性，以及影响输出的图形模式。 此方法返回该设备上下文（字体除外）。由于未选择字体，使用 GetHdc 方法返回的句柄对 FromHdc 方法进行调用将会失败。
GetHdc 方法调用和 ReleaseHdc 方法调用必须成对出现。 在 GetHdc 和 ReleaseHdc 方法对的范围内，通常仅调用 GDI 函数。 在该范围内对 Graphics（它产生 hdc 参数）的 GDI+ 方法的调用因 ObjectBusy 错误而失败。 此外，GDI+ 忽略后续操作中对 hdc 参数的 Graphics 所做的所有状态更改。
示例
下面的代码示例设计为与 Windows 窗体一起使用，它需要 PaintEventArgse，即 Paint 事件处理程序的一个参数。 该示例演示如何调用 Windows GDI 函数以执行与 GDI+ Graphics 方法相同的任务。 代码执行下列操作：
为 Windows DLL 文件 gdi32.dll 定义互操作性 DllImportAttribute 特性。 此 DLL 包含所需的 GDI 函数。 将该 DLL 中的 Rectangle 函数定义为外部函数。 创建一支红色钢笔。 利用该钢笔，使用 GDI+ DrawRectangle 方法将矩形绘制到屏幕。 定义内部指针类型变量 hdc 并将它的值设置为窗体的设备上下文句柄。 使用 GDI Rectangle 函数将矩形绘制到屏幕。释放由 hdc 参数表示的设备上下文。
public class GDI
{
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
internal static extern bool Rectangle(
IntPtr hdc,
int ulCornerX, int ulCornerY,
int lrCornerX, int lrCornerY);
}
[System.Security.Permissions.SecurityPermission(
System.Security.Permissions.SecurityAction.LinkDemand, Flags =
System.Security.Permissions.SecurityPermissionFlag.UnmanagedCode)]
private void GetHdcForGDI1(PaintEventArgs e)
{
// Create pen.
Pen redPen = new Pen(Color.Red, 1);
// Draw rectangle with GDI+.
e.Graphics.DrawRectangle(redPen, 10, 10, 100, 50);
// Get handle to device context.
IntPtr hdc = e.Graphics.GetHdc();
// Draw rectangle with GDI using default pen.
GDI.Rectangle(hdc, 10, 70, 110, 120);
// Release handle to device context.
e.Graphics.ReleaseHdc(hdc);
}
