C#图像处理.docx

1、C#图像处理一Bitmap类Bitmap对象封装了+中的一个位图，此位图由图形图像及其属性的像素数据组成.因此Bitmap是用于处理由像素数据定义的图像的对象.该类的主要方法和属性如下：1. GetPixel方法和 SetPixel方法：获取和设置一个图像的指定像素的颜色.2. PixelFormat属性：返回图像的像素格式.3. Palette属性：获取和设置图像所使用的颜色调色板.4. Height Width属性：返回图像的高度和宽度.5. LockBits 方法和UnlockBits方法：分别锁定和解锁系统内存中的位图像素.在基于像素点的图像处理方法中使用LockBits 和Unloc

2、kBits是一个很好的方式，这两种方法可以使我们指定像素的范围来控制位图的任意一部分，从而消除了通过循环对位图的像素逐个进行处理，每调用LockBits 之后都应该调用一次UnlockBits. 二BitmapData类BitmapData对象指定了位图的属性1. Height属性：被锁定位图的高度.2. Width属性：被锁定位图的高度.3. PixelFormat属性：数据的实际像素格式.4. Scan0属性：被锁定数组的首字节地址，如果整个图像被锁定，则是图像的第一个字节地址.5. Stride属性：步幅，也称为扫描宽度.如上图所示,数组的长度并不一定等于图像像素数组的长度,还有一部分未

3、用区域,这涉及到位图的数据结构,系统要保证每行的字节数必须为4的倍数. 三Graphics类Graphics对象是+的关键所在，许多对象都是由Graphics类表示的，该类定义了绘制和填充图形对象的方法和属性，一个应用程序只要需要进行绘制或着色，它就必须使用Graphics对象. 四Image类这个类提供了位图和元文件操作的函数.Image类被声明为abstract,也就是说Image类不能实例化对象,而只能做为一个基类.1.FromFile方法：它根据输入的文件名产生一个Image对象,它有两种函数形式:public static Image FromFile(string filename

4、);public static Image FromFile(string filename, bool useEmbeddedColorManagement);2.FromHBitmap方法：它从一个windows句柄处创建一个bitmap对象, 它也包括两种函数形式:public static bitmap fromhbitmap(intptr hbitmap);public static bitmap fromhbitmap(intptr hbitmap, intptr hpalette);3. FromStream方法：从一个数据流中创建一个image对象,它包含三种函数形式 :pub

5、lic static image fromstream(stream stream);public static image fromstream(stream stream, bool useembeddedcolormanagement);fromstream(stream stream, bool useembeddedcolormanagement, bool validateimagedata); 有了上面的了解，我们便可以开始利用#做图像处理，下面介绍几种方法：一. 打开、保存、显示图像 private Bitmap srcBitmap = null; private Bitmap

6、 showBitmap = null;/打开文件private void menuFileOpen_Click(object sender, EventArgs e)OpenFileDialog openFileDialog = new OpenFileDialog();openFileDialog.Filter = Bitmap文件(*.bmp)|*.bmp|Jpeg文件(*.jpg)|*.jpg|所有合适文件(*.bmp,*.jpg)|*.bmp;*.jpg;openFileDialog.FilterIndex = 3;openFileDialog.RestoreDirectory = t

7、rue;if (DialogResult.OK = openFileDialog.ShowDialog()srcBitmap = (Bitmap)Bitmap.FromFile(openFileDialog.FileName, false);showBitmap = srcBitmap;this.AutoScroll = true;this.AutoScrollMinSize = new Size(int)(showBitmap.Width), (int)(showBitmap.Height);this.Invalidate(); /保存图像文件private void menuFileSav

8、e_Click(object sender, EventArgs e)if (showBitmap != null)SaveFileDialog saveFileDialog = new SaveFileDialog();saveFileDialog.Filter = Bitmap文件(*.bmp)|*.bmp|Jpeg文件(*.jpg)|*.jpg|所有合适文件(*.bmp,*.jpg)|*.bmp;*.jpg;saveFileDialog.FilterIndex = 3;saveFileDialog.RestoreDirectory = true;if (DialogResult.OK =

9、 saveFileDialog.ShowDialog() ImageFormat format = ImageFormat.Jpeg;switch (Path.GetExtension(saveFileDialog.FileName).ToLower()case .jpg:format = ImageFormat.Jpeg;break;case .bmp:format = ImageFormat.Bmp;break;default:MessageBox.Show(this, Unsupported image format was specified, Error,MessageBoxButt

10、ons.OK, MessageBoxIcon.Error);return;tryshowBitmap.Save(saveFileDialog.FileName,format );catch (Exception)MessageBox.Show(this, Failed writing image file, Error,MessageBoxButtons.OK, MessageBoxIcon.Error);/窗口重绘,在窗体上显示图像,重载Paintprivate void frmMain_Paint(object sender, System.Windows.Forms.PaintEvent

11、Args e)if (showBitmap != null) Graphics g = e.Graphics;g.DrawImage(showBitmap, new Rectangle(this.AutoScrollPosition.X, this.AutoScrollPosition.Y ,(int)(showBitmap.Width), (int)(showBitmap.Height); /灰度化private void menu2Gray_Click(object sender, EventArgs e)if (showBitmap = null) return;showBitmap =

12、 RGB2Gray(showBitmap);/下面都以RGB2Gray为例this.Invalidate();二. 提取像素法这种方法简单易懂,但相当耗时,完全不可取.public static Bitmap RGB2Gray(Bitmap srcBitmap)Color srcColor;int wide = srcBitmap.Width;int height = srcBitmap.Height;for (int y = 0; y height; y+)for (int x = 0; x wide; x+)/获取像素的颜色值srcColor = srcBitmap.GetPixel(x,

13、 y);byte temp = (byte)(srcColor.R * .299 + srcColor.G * .587 + srcColor.B * .114);/设置像素的颜色值 srcBitmap.SetPixel(x, y, Color.FromArgb(temp, temp, temp);return srcBitmap ;/# 三. 内存法这是比较常用的方法public static Bitmap RGB2Gray(Bitmap srcBitmap)int wide = srcBitmap.Width; int height = srcBitmap.Height;Rectangle

14、 rect = new Rectangle(0, 0, wide, height);/ 将Bitmap锁定到系统内存中, 获得BitmapDataBitmapData srcBmData = srcBitmap.LockBits(rect,ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);/创建BitmapBitmap dstBitmap = CreateGrayscaleImage(wide, height);/这个函数在后面有定义BitmapData dstBmData = dstBitmap.LockBits(rect,ImageL

15、ockMode.ReadWrite, PixelFormat.Format8bppIndexed);/ 位图中第一个像素数据的地址。它也可以看成是位图中的第一个扫描行System.IntPtr srcPtr = srcBmData.Scan0;System.IntPtr dstPtr = dstBmData.Scan0;/ 将Bitmap对象的信息存放到byte数组中int src_bytes = srcBmData.Stride * height;byte srcValues = new bytesrc_bytes;int dst_bytes = dstBmData.Stride * hei

16、ght;byte dstValues = new bytedst_bytes;/复制GRB信息到byte数组System.Runtime.InteropServices.Marshal.Copy(srcPtr, srcValues, 0, src_bytes);System.Runtime.InteropServices.Marshal.Copy(dstPtr, dstValues, 0, dst_bytes);/ 根据Y=0.299*R+0.114*G+0.587B,Y为亮度for (int i = 0; i height; i+)for (int j = 0; j wide; j+) /只

17、处理每行中图像像素数据,舍弃未用空间/注意位图结构中RGB按BGR的顺序存储int k = 3 * j;byte temp = (byte)(srcValuesi * srcBmData.Stride + k + 2 * .299+ srcValuesi * srcBmData.Stride + k + 1 * .587 + srcValuesi * srcBmData.Stride + k * .114);dstValuesi * dstBmData.Stride + j = temp;/将更改过的byte拷贝到原位图System.Runtime.InteropServices.Marsha

18、l.Copy(dstValues, 0, dstPtr, dst_bytes);/ 解锁位图srcBitmap.UnlockBits(srcBmData);dstBitmap.UnlockBits(dstBmData);return dstBitmap;/#四 指针法C/C+的习惯,不是C#的特点public static Bitmap RGB2Gray(Bitmap srcBitmap)int wide = srcBitmap.Width;int height = srcBitmap.Height ;Rectangle rect = new Rectangle(0, 0, wide, hei

19、ght);BitmapData srcBmData = srcBitmap.LockBits(rect,ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);Bitmap dstBitmap = CreateGrayscaleImage(wide, height);BitmapData dstBmData = dstBitmap.LockBits(rect,ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed); System.IntPtr srcScan = srcBmData.Sca

20、n0;System.IntPtr dstScan = dstBmData.Scan0;Unsafe /启动不安全代码byte* srcP = (byte*)(void*) srcScan;byte* dstP = (byte*)(void*) dstScan;int srcOffset = srcBmData.Stride - wide * 3;int dstOffset = dstBmData.Stride - wide ;byte red, green, blue;for (int y = 0; y height; y+)for (int x = 0; x wide ; x+, srcP

21、+= 3, dstP+)blue = srcP 0;green = srcP 1;red = srcP 2;* dstP = (byte)(.299 * red + .587 * green + .114 * blue);srcP += srcOffset;dstP += dstOffset;srcBitmap.UnlockBits(srcBmData);dstBitmap.UnlockBits(dstBmData );return dstBitmap;/#五. 矩阵法并不是什么新方法,只是将图像数据分做R,G,B三个矩阵(二维数组)存储,类似MATLAB的习惯.public static b

22、ool GetRGB(Bitmap Source, out int, R, out int, G, out int, B)tryint iWidth = Source.Width;int iHeight = Source.Height;Rectangle rect = new Rectangle(0, 0, iWidth, iHeight);System.Drawing.Imaging.BitmapData bmpData = Source.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, Source.PixelFo

23、rmat);IntPtr iPtr = bmpData.Scan0;int iBytes = iWidth * iHeight * 3;byte PixelValues = new byteiBytes;System.Runtime.InteropServices.Marshal.Copy(iPtr, PixelValues, 0, iBytes);Source.UnlockBits(bmpData);/ 注意这个地方图像的两维方向与数组两维的方向是转置的关系 R = new intiHeight, iWidth;G = new intiHeight, iWidth;B = new intiH

24、eight, iWidth;int iPoint = 0;for (int i = 0; i iHeight; i+)for (int j = 0; j iWidth; j+)/ 注意，Windows 中三基色的排列顺序是 BGR 而不是 RGB！ Bi, j = Convert.ToInt32(PixelValuesiPoint+);Gi, j = Convert.ToInt32(PixelValuesiPoint+);Ri, j = Convert.ToInt32(PixelValuesiPoint+);return true;catch (Exception)R = null;G = n

25、ull;B = null;return false;/#public static Bitmap FromRGB(int, R, int, G, int, B)int iWidth = G.GetLength(1);int iHeight = G.GetLength(0);Bitmap Result = new Bitmap(iWidth, iHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);Rectangle rect = new Rectangle(0, 0, iWidth, iHeight);System.Drawing

26、.Imaging.BitmapData bmpData = Result.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);IntPtr iPtr = bmpData.Scan0;int iStride = bmpData.Stride; int iBytes = iWidth * iHeight * 3;byte PixelValues = new byteiBytes;int iPoint = 0;for (int

27、 i = 0; i iHeight; i+)for (int j = 0; j iWidth; j+)int iG = Gi, j;int iB = Bi, j;int iR = Ri, j;PixelValuesiPoint = Convert.ToByte(iB);PixelValuesiPoint + 1 = Convert.ToByte(iG);PixelValuesiPoint + 2 = Convert.ToByte(iR);iPoint += 3;System.Runtime.InteropServices.Marshal.Copy(PixelValues, 0, iPtr, i

28、Bytes);Result.UnlockBits(bmpData);return Result;/#public static bool GetGray(Bitmap srcBitmap, out byte , gray)Bitmap tempBitmap;if (srcBitmap.PixelFormat != PixelFormat.Format8bppIndexed)tempBitmap = ImageProcess.Image.Gray(srcBitmap);elsetempBitmap = srcBitmap;int wide = tempBitmap.Width;int heigh

29、t = tempBitmap.Height;gray = new byte height, wide;BitmapData gbmData = tempBitmap.LockBits(new Rectangle(0, 0, wide, height),ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);System.IntPtr ScanG = gbmData.Scan0;int gOffset = gbmData.Stride - wide;unsafebyte* g = (byte*)(void*)ScanG;/ for each

30、 pixelfor (int y = 0; y height; y+)/ for each pixelfor (int x = 0; x wide; x+, g+)grayy ,x =*g;g += gOffset;tempBitmap.UnlockBits(gbmData);return true ;/#public static Bitmap FromGray(byte , Gray)int iWidth = Gray.GetLength(1);int iHeight = Gray.GetLength(0);Bitmap dstBitmap = ImageProcess.Image.CreateGrayscaleImage(iWidth, iHeight);BitmapData gbmData = dstBitmap.LockBits(new Rectangle(0, 0, iWidth, iH