2014-09-19 08:39:03 coobeedongzhou 阅读数 6597
  • C#急速入门

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c#图像处理入门

-bitmap类和图像像素值获取方法

 转自http://blog.csdn.net/jiangxinyu/article/details/6222302

一.Bitmap类

Bitmap对象封装了GDI+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UnlockBits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GDI+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);

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:

public 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C#做图像处理,下面介绍几种方法:

一.   打开、保存、显示图像

        privateBitmap srcBitmap = null;

          privateBitmap showBitmap = null;

        //打开文件

        privatevoid menuFileOpen_Click(object sender, EventArgs e)

        {

            OpenFileDialog openFileDialog = newOpenFileDialog();

            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 = true;

            if (DialogResult.OK == openFileDialog.ShowDialog())

            {

                srcBitmap = (Bitmap)Bitmap.FromFile(openFileDialog.FileName, false);

                showBitmap = srcBitmap;

                this.AutoScroll = true;

                this.AutoScrollMinSize =

newSize((int)(showBitmap.Width), (int)(showBitmap.Height));

                this.Invalidate();

             }

        }

        //保存图像文件

        privatevoid menuFileSave_Click(object sender, EventArgs e)

        {

            if (showBitmap != null)

            {

                SaveFileDialog saveFileDialog = newSaveFileDialog();

                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 == 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",

                                MessageBoxButtons.OK, MessageBoxIcon.Error);

                            return;

                    }

                    try

                    {

                        showBitmap.Save(saveFileDialog.FileName,format );

                    }

                    catch (Exception)

                    {

                        MessageBox.Show(this, "Failed writing image file", "Error",

                            MessageBoxButtons.OK, MessageBoxIcon.Error);

                    }

                }

            }

        }

 

c#中将bitmap或者image保存为清晰的gif

在c#中默认可以讲bitmap保存为gif等格式,但是这种保存方法保存的gif会严重失真,正常情况下的代码:

1 System.Drawing.Bitmap b = new System.Drawing.Bitmap(“c://original_image.gif“); 
2   System.Drawing.Image thmbnail = b.GetThumbnailImage(100,75,null,new IntPtr()); 

3   thmbnail.Save(“c://thumnail.gif“, System.Drawing.Imaging.ImageFormat.Gif); 

一个批量处理图片的软件,包括各种处理方式,处理效果,但是在保存为gif的时候出现了问题,在网上查了很久也没有发现一个可用的改善gif图片质量的方法,找到了一个解决办法,保存出来的gif容量大减,但是效果基本符合常规这中方法就是就是“Octree“ 算法。

“Octree“ 算法允许我们插入自己的算法来量子化我们的图像。

 

一个好的“颜色量子化”算法应该考虑在两个像素颗粒之间填充与这两个像素颜色相近的过渡颜色,提供更多可视颜色空间。

 

Morgan Skinner提供了很好的“Octree“ 算法代码,大家可以下载参考使用。

 

  使用OctreeQuantizer很方便:

 System.Drawing.Bitmap b = new System.Drawing.Bitmap(“c://original_image.gif“);

 System.Drawing.Image thmbnail = b.GetThumbnailImage(100,75,null,new IntPtr());

 OctreeQuantizer quantizer = new OctreeQuantizer ( 255 , 8 ) ;

 using ( Bitmap quantized = quantizer.Quantize ( thmbnail ) )

 {

   quantized.Save(“c://thumnail.gif“, System.Drawing.Imaging.ImageFormat.Gif);

 }

 OctreeQuantizer grayquantizer = new GrayscaleQuantizer ( ) ;

 using ( Bitmap quantized = grayquantizer.Quantize ( thmbnail ) )

 {

   quantized.Save(“c://thumnail.gif“, System.Drawing.Imaging.ImageFormat.Gif);

}

你可以点击这里下载类的文件(项目文件),根据我的试用,只需要两个类文件(OctreeQuantizer.cs,Quantizer.cs)即可运行,将这两个类文件的namespace改成你项目的名称就行,还有,需要在不安全编译的方式下编译,右击项目名称,在生成选项卡里选择"允许不安全代码"即可

 

 

    //窗口重绘,在窗体上显示图像,重载Paint

        privatevoid frmMain_Paint(object sender, System.Windows.Forms.PaintEventArgs e)

        {

            if (showBitmap != null)

            {

                Graphics g = e.Graphics;

                g.DrawImage(showBitmap, newRectangle(this.AutoScrollPosition.X, this.AutoScrollPosition.Y ,

                (int)(showBitmap.Width), (int)(showBitmap.Height)));

            }

        }

         //灰度化

        privatevoid menu2Gray_Click(object sender, EventArgs e)

        {

            if (showBitmap == null) return;

            showBitmap = 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.

publicstaticBitmap 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RGB颜色值

                    srcColor = srcBitmap.GetPixel(x, y);

                    byte temp = (byte)(srcColor.R * .299 + srcColor.G * .587 + srcColor.B * .114);

                    //设置像素的RGB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

publicstaticBitmap RGB2Gray(Bitmap srcBitmap)

        {

            int wide = srcBitmap.Width;

            int height = srcBitmap.Height;

            Rectangle rect = newRectangle(0, 0, wide, height);

            //将Bitmap锁定到系统内存中,获得BitmapData

            BitmapData srcBmData = srcBitmap.LockBits(rect,

                      ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

            //创建Bitmap

             Bitmap dstBitmap = CreateGrayscaleImage(wide, height);//这个函数在后面有定义

            BitmapData dstBmData = dstBitmap.LockBits(rect,

                      ImageLockMode.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 = newbyte[src_bytes];

            int dst_bytes = dstBmData.Stride * height;

            byte[] dstValues = newbyte[dst_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)(srcValues[i * srcBmData.Stride + k + 2] * .299

                         + srcValues[i * srcBmData.Stride + k + 1] * .587

+ srcValues[i * srcBmData.Stride + k] * .114);

                    dstValues[i * dstBmData.Stride + j] = temp;

                }

            System.Runtime.InteropServices.Marshal.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

publicstaticBitmap RGB2Gray(Bitmap srcBitmap)

        {

            int wide = srcBitmap.Width;

            int height = srcBitmap.Height ;

            Rectangle rect = newRectangle(0, 0, wide, height);

            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.Scan0;

            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 += 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.

       publicstaticbool GetRGB(Bitmap Source, outint[,] R, outint[,] G, outint[,] B)

        {

            try

            {

                int iWidth = Source.Width;

                int iHeight = Source.Height; 

                Rectangle rect = newRectangle(0, 0, iWidth, iHeight);

                System.Drawing.Imaging.BitmapData bmpData = Source.LockBits(rect,

System.Drawing.Imaging.ImageLockMode.ReadWrite, Source.PixelFormat);

                IntPtr iPtr = bmpData.Scan0; 

                int iBytes = iWidth * iHeight * 3;

                byte[] PixelValues = new byte[iBytes];

                System.Runtime.InteropServices.Marshal.Copy(iPtr, PixelValues, 0, iBytes);

                Source.UnlockBits(bmpData); 

                R = newint[iHeight, iWidth];

                G = newint[iHeight, iWidth];

                B = newint[iHeight, iWidth]; 

                int iPoint = 0; 

                for (int i = 0; i < iHeight; i++)

                {

                    for (int j = 0; j < iWidth; j++)

                    {

                        B[i, j] = Convert.ToInt32(PixelValues[iPoint++]);

                        G[i, j] = Convert.ToInt32(PixelValues[iPoint++]);

                        R[i, j] = Convert.ToInt32(PixelValues[iPoint++]);

                    }

                } 

                return true;

            }

            catch (Exception)

            {

                R = null;

                G = null;

                B = null; 

                returnfalse;

            }

        }

        publicstaticBitmap FromRGB(int[,] R, int[,] G, int[,] B)

        {

            int iWidth = G.GetLength(1);

            int iHeight = G.GetLength(0);

            Bitmap Result = newBitmap(iWidth, iHeight,

System.Drawing.Imaging.PixelFormat.Format24bppRgb); 

            Rectangle rect = newRectangle(0, 0, iWidth, iHeight);

            System.Drawing.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 = newbyte[iBytes];

            int iPoint = 0; 

            for (int i = 0; i < iHeight; i++)

                for (int j = 0; j < iWidth; j++)

                {

                    int iG = G[i, j];

                    int iB = B[i, j];

                    int iR = R[i, j];

                    PixelValues[iPoint] = Convert.ToByte(iB);

                    PixelValues[iPoint + 1] = Convert.ToByte(iG);

                    PixelValues[iPoint + 2] = Convert.ToByte(iR);

                    iPoint += 3;

                }

             System.Runtime.InteropServices.Marshal.Copy(PixelValues, 0, iPtr, iBytes);

             Result.UnlockBits(bmpData);

             return Result;

        }

        publicstaticbool GetGray(Bitmap srcBitmap, outbyte [,] gray)

        { 

            Bitmap tempBitmap;

            if (srcBitmap.PixelFormat != PixelFormat.Format8bppIndexed)

                tempBitmap = ImageProcess.Image.Gray(srcBitmap);

            else

                tempBitmap = srcBitmap;

 

            int wide = tempBitmap.Width;

            int height = tempBitmap.Height;

            gray = newbyte [height, wide];

            BitmapData gbmData = tempBitmap.LockBits(newRectangle(0, 0, wide, height),

                  ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);

            System.IntPtr ScanG = gbmData.Scan0;

            int gOffset = gbmData.Stride - wide;

            unsafe

            {

                byte* g = (byte*)(void*)ScanG;

                for (int y = 0; y < height; y++)

                {

                    for (int x = 0; x < wide; x++, g++)

                    {

                        gray[y ,x ] =*g;

                    }

                    g += gOffset;

                }

            }

             tempBitmap.UnlockBits(gbmData);

            returntrue ;

         }

        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(newRectangle(0, 0, iWidth, iHeight),

                      ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);

            System.IntPtr ScanG = gbmData.Scan0;

            int gOffset = gbmData.Stride - iWidth;

            unsafe

            {

                byte* g = (byte*)(void*)ScanG; 

                for (int i = 0; i < iHeight; i++)

                {

                    for (int j = 0; j < iWidth; j++)

                    {

                        *g=(byte )Gray[i, j] ;

                        g++;

                    }

                    g += gOffset;

                }

            } 

            dstBitmap.UnlockBits(gbmData); 

            return dstBitmap;

        }

         ///<summary>

         /// Create and initialize grayscale image

         ///</summary>

         publicstaticBitmap CreateGrayscaleImage( int width, int height )

         {

              // create new image

              Bitmap bmp = newBitmap( width, height, PixelFormat.Format8bppIndexed );

              // set palette to grayscale

              SetGrayscalePalette( bmp );

              // return new image

              return bmp;

         }//#

         ///<summary>

         /// Set pallete of the image to grayscale

         ///</summary>

         publicstaticvoid SetGrayscalePalette( Bitmap srcImg )

         {

              // check pixel format

              if ( srcImg.PixelFormat != PixelFormat.Format8bppIndexed )

                   thrownewArgumentException( );

              // get palette

              ColorPalette cp = srcImg.Palette;

              // init palette

              for ( int i = 0; i < 256; i++){

                   cp.Entries[i] = Color.FromArgb( i, i, i );

              }

              srcImg.Palette = cp;

         }

 

C#数字图像处理的3种典型方法(精简版)

 

C#数字图像处理有3种典型方法:提取像素法、内存法、指针法。其中提取像素法使用的是GDI+中的Bitmap.GetPixel和Bitmap.SetPixel方法;内存法是通过LockBits方法来获取位图的首地址,从而把图像数据直接复制到内存中进行处理;指针法与内存法相似,但该方法直接应用指针对位图进行操作,由于在默认情况下,C#不支持指针运算,所以该方法只能在unsafe关键字所标记的代码块中使用。以一幅真彩色图像的灰度化为例,下面代码分别展现了这3种方法的使用,方便大家学习图像处理的基本技巧。

(1) 像素提取法

if (curBitmap != null)

{

      Color curColor;

      int gray;

      for (int i = 0; i < curBitmap.Width; i++)

      {

             for (int j = 0; j < curBitmap.Height; j++)

             {

                    curColor = curBitmap.GetPixel(i, j);

                    gray = (int)(0.3 * curColor.R + 0.59 * curColor.G * 0.11 * curColor.B);

                    curBitmap.SetPixel(i, j, curColor);

             }

      }

}

(2) 内存法

if (curBitmap != null)

{

      int width = curBitmap.Width;

      int height = curBitmap.Height;

      int length = height * 3 * width;

      RGB = new byte[length];

     BitmapData data = curBitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

      System.IntPtr Scan0 = data.Scan0;

      System.Runtime.InteropServices.Marshal.Copy(Scan0, RGB, 0, length);

      double gray = 0;

      for (int i = 0; i < RGB.Length; i=i+3)

      {

             gray = RGB[i + 2] * 0.3 + RGB[i + 1] * 0.59 + RGB[i] * 0.11;

             RGB[i + 2] = RGB[i + 1] = RGB[i] = (byte)gray;

      }

      System.Runtime.InteropServices.Marshal.Copy(RGB, 0, Scan0, length);

      curBitmap.UnlockBits(data);

}

(3) 指针法

if (curBitmap != null)

{

      int width = curBitmap.Width;

      int height = curBitmap.Height;

     BitmapData data = curBitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

      System.IntPtr Scan0 = data.Scan0;

      int stride = data.Stride;

      System.Runtime.InteropServices.Marshal.Copy(Scan0, RGB, 0, length);

      unsafe

      {

             byte* p = (byte*)Scan0;

             int offset = stride - width * 3;

             double gray = 0;

             for (int y = 0; y < height; y++)

             {

                    for (int x = 0; x < width; x++)

                    {

                           gray = 0.3 * p[2] + 0.59 * p[1] + 0.11 * p[0];

                           p[2] = p[1] = p[0] = (byte)gray;

                           p += 3;

                    }

                    p += offset;

             }

      }

      curBitmap.UnlockBits(data);

         }

在以上3种方法中,提取像素法能直观的展示图像处理过程,可读性很好,但效率最低,并不适合做图像处理方面的工程应用;内存法把图像直接复制到内存中,直接对内存中的数据进行处理,速度明显提高,程序难度也不大;指针法直接应用指针来对图像进行处理,所以速度最快。

 

 

简单图片处理函数代码(C#

 

一、生成图片并实现颜色渐变效果 
    Response.Clear(); 
    Bitmap imgOutput = new Bitmap(100, 50); 
    Graphics gic = Graphics.FromImage(imgOutput);

gic.Clear(Color.BlueViolet); 
    gic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; 
    gic.DrawString("渐变图形", new Font("黑体",16,FontStyle.Italic),

new SolidBrush(Color.White),new PointF(2,2)); 
    gic.FillRectangle(new System.Drawing.Drawing2D.LinearGradientBrush(new Point(0,0),

new Point(100,50), Color.FromArgb(0,0,0,0),

Color.FromArgb(255,255,255,255)),0,0,100,50);

    imgOutput.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg); 
    gic.Dispose(); 
    imgOutput.Dispose(); 
    Response.End(); 

二、对图片进行反转 
    System.Drawing.Image drawimage = System.Drawing.Image.FromFile(photopath);//photopath表示图片的物理地址 
    drawimage.RotateFlip(RotateFlipType.Rotate270FlipNone); 
    if(File.Exists(photopath)) 
    { 
         File.SetAttributes(photopath,FileAttributes.Normal); 
         File.Delete(photopath); 
    } 
    drawimage.Save(photopath,System.Drawing.Imaging.ImageFormat.Jpeg); 
    drawimage.Dispose(); 

三、对图片进行缩放 
    System.Drawing.Image drawimage = System.Drawing.Image.FromFile(photopath); 
    Bitmap imgOutput = new Bitmap(drawimage,60,30); 
    imgOutput.Save(newphotppath, System.Drawing.Imaging.ImageFormat.Jpeg); 
    imgOutput.Dispose();   
    Response.End(); 

其他还有一些画线、画矩形、画圆等的函数和方法都可以在System.Drawing中找到;

本文的实例是一个数字图像处理的应用程序,它完成的功能包括对图像颜色的翻转、对图像进行灰度处理和对图像进行增亮处理。该程序对图像进行处理部分的代码包含在一个专门的Filters类里面,通过调用该类里的静态成员函数,我们就可以实现相应的图像处理功能了。为实现图像处理,我们要对图像进行逐个象素处理。我们知道图像是由一个个的象素点组成的,对一幅图像的每个象素进行了相应的处理,最后整个图像也就处理好了。在这个过程中,我们只需对每个象素点进行相应的处理,在处理过程中却不需要考虑周围象素点对其的影响,所以相对来说程序的实现就变得简单多了。

  由于GDI+中的BitmapData类不提供对图像内部数据的直接访问的方法,我们唯一的办法就是使用指针来获得图像的内部数据,这时我们就得运用unsafe这个关键字来指明函数中访问图像内部数据的代码块了。在程序中,我还运用了打开文件和保存文件等选项,以使我们的辛勤劳动不付之东流。

  二.程序的实现:

  

Invert()、Gray()、Brightness()等三个函数均包含在Filters类里面,

Invert()函数的算法如下:

public static bool Invert(Bitmap b)

 {

 BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height),

    ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

 int stride = bmData.Stride;

 System.IntPtr Scan0 = bmData.Scan0;

 unsafe

 {

  byte * p = (byte *)(void *)Scan0;

  int nOffset = stride - b.Width*3;

  int nWidth = b.Width * 3;

  for(int y=0;y<b.Height;++y)

  {

   for(int x=0; x < nWidth; ++x )

   {

    p[0] = (byte)(255-p[0]);

    ++p;

   }

   p += nOffset;

  }

 }

 b.UnlockBits(bmData);

 return true;

 }

该函数以及后面的函数的参数都是Bitmap类型的,它们传值的对象就是程序中所打开的图像文件了。该函数中的BitmapData类型的bmData包含了图像文件的内部信息,bmData的Stride属性指明了一条线的宽度,而它的Scan0属性则是指向图像内部信息的指针。本函数完成的功能是图像颜色的翻转,实现的方法即用255减去图像中的每个象素点的值,并将所得值设置为原象素点处的值,对每个象素点进行如此的操作,只到整幅图像都处理完毕。函数中的unsafe代码块是整个函数的主体部分,首先我们取得图像内部数据的指针,然后设置好偏移量,同时设置nWidth为b.Width*3,因为每个象素点包含了三种颜色成分,对每个象素点进行处理时便要进行三次处理。接下来运用两个嵌套的for循环完成对每个象素点的处理,处理的核心便是一句:p[0] = (byte)(255-p[0]);。在unsafe代码块后,便可运用b.UnlockBits(bmData)进行图像资源的释放。函数执行成功,最后返回true值。注:由于是要编译不安全代码,所以得将项目属性页中的"允许不安全代码块"属性设置为true,

 

Gray()函数的算法如下:

public static bool Gray(Bitmap b)

 {

        BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height),

                  ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

 int stride = bmData.Stride;

 System.IntPtr Scan0 = bmData.Scan0;

 unsafe

 {

  byte * p = (byte *)(void *)Scan0;

  int nOffset = stride - b.Width*3;

  byte red, green, blue;

  for(int y=0;y<b.Height;++y)

 {

    for(int x=0; x < b.Width; ++x )

  {

   blue = p[0];

   green = p[1];

   red = p[2];

   p[0] = p[1] = p[2] = (byte)(.299 * red + .587 * green + .114 * blue);

   p += 3;

  }

  p += nOffset;

 }

 }

 b.UnlockBits(bmData);

 return true;

 }

  本函数完成的功能是对图像进行灰度处理,我们的基本想法可是将每个象素点的三种颜色成分的值取平均值。然而由于人眼的敏感性,这样完全取平均值的做法的效果并不好,所以在程序中我取了三个效果最好的参数:.299,.587,.114。不过在这里要向读者指明的是,在GDI+中图像存储的格式是BGR而非RGB,即其顺序为:Blue、Green、Red。所以在for循环内部一定要设置好red、green、blue等变量的值,切不可颠倒。函数执行成功后,同样返回true值。

 

Brightness()函数的算法如下:

public static bool Brightness(Bitmap b, int nBrightness)

 {

  if (nBrightness < -255 || nBrightness > 255)

   return false;

  BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width,

                                    b.Height), ImageLockMode.ReadWrite,

                                    PixelFormat.Format24bppRgb);

  int stride = bmData.Stride;

  System.IntPtr Scan0 = bmData.Scan0;

  int nVal = 0;

  unsafe

  {

   byte * p = (byte *)(void *)Scan0;

   int nOffset = stride - b.Width*3;

   int nWidth = b.Width * 3;

   for(int y=0;y<b.Height;++y)

   {

      for(int x=0; x < nWidth; ++x )

       {

    nVal = (int) (p[0] + nBrightness);

    if (nVal < 0) nVal = 0;

    if (nVal > 255) nVal = 255;

    p[0] = (byte)nVal;

    ++p;

        }

       p += nOffset;

   }

  }

  b.UnlockBits(bmData);

  return true;

 }

  本函数完成的功能是对图像进行增亮处理,它比上面两个函数多了一个增亮参数-nBrightness,该参数由用户输入,范围为-255~255。在取得了增亮参数后,函数的unsafe代码部分对每个象素点的不同颜色成分进行逐个处理,即在原来值的基础上加上一个增亮参数以获得新的值。同时代码中还有一个防止成分值越界的操作,因为RGB成分值的范围为0~255,一旦超过了这个范围就要重新设置。函数最后执行成功后,同样得返回true值。

  该函数实现的程序效果如下:

 

  首先,我们把图像增亮的参数设置为100(其范围为-255~255),然后执行效果如下,读者也可尝试其他的参数值。

 

  三.小结:

  本文通过一个简单的实例向大家展现了用Visual C#以及GDI+完成数字图像处理的基本方法,通过实例,我们不难发现合理运用新技术不仅可以大大简化我们的编程工作,还可以提高编程的效率。不过我们在运用新技术的同时也得明白掌握基本的编程思想才是最主要的,不同的语言、不同的机制只是实现的具体方式不同而已,其内在的思想还是相通的。对于上面的例子,掌握了编写图像处理函数的算法,用其他的方式实现也应该是可行的。同时,在上面的基础上,读者不妨试着举一反三,编写出更多的图像处理的函数来,以充实并完善这个简单的实例。

image与byte数组的转换

image to byte[]

  MemoryStream ms=new MemoryStream();
   byte[] imagedata=null;
   pictureBox1.Image.Save(ms,System.Drawing.Imaging.ImageFormat.Gif );
   imagedata=ms.GetBuffer ();

byte[] to image

  ms = New IO.MemoryStream(by)
  img = Drawing.Image.FromStream(ms)
2016-08-12 15:12:59 scimence 阅读数 3879
  • C#急速入门

    Unity开发,C#绝对是基础中的基础,课程针对纯小白而设计,各种语言细节在课程里均有涉猎,从原理到实战,从底层到算法,你想了解的C#,这里应有尽有,除了讲解,还有练习,你说棒不棒,哈哈,当然如果你是有其他语言基础的同学,课程依然会让你收货满满。来吧,我们进入正题。 C#语言系列课程分为五个部分: 1.C#急速入门 2.C#之面向对象 观看地址:https://edu.csdn.net/course/detail/9447 3.C#高级进阶(期待中……) 4.程序员内功修炼 - 数据结构(C#) 观看地址: https://edu.csdn.net/course/detail/10505 5.Unity百家公司面试题总结  C#部分(期待中……)    #此后新课程更新将在张建飞老师个人账号下发布 敬请关注~~ https://edu.csdn.net/lecturer/2528

    21740 人正在学习 去看看 张建飞

示例:

Image screen = getScreen();                       // 截取屏幕
saveImage(screen, screen.Size, @"d:\截屏.jpg");   // 保存截屏

# region 图像处理功能函数

/// <summary>
/// 按指定尺寸对图像pic进行非拉伸缩放
/// </summary>
public static Bitmap shrinkTo(Image pic, Size S, Boolean cutting)
{
    //创建图像
    Bitmap tmp = new Bitmap(S.Width, S.Height);     //按指定大小创建位图

    //绘制
    Graphics g = Graphics.FromImage(tmp);           //从位图创建Graphics对象
    g.Clear(Color.FromArgb(0, 0, 0, 0));            //清空

    Boolean mode = (float)pic.Width / S.Width > (float)pic.Height / S.Height;   //zoom缩放
    if (cutting) mode = !mode;                      //裁切缩放

    //计算Zoom绘制区域             
    if (mode)
        S.Height = (int)((float)pic.Height * S.Width / pic.Width);
    else
        S.Width = (int)((float)pic.Width * S.Height / pic.Height);
    Point P = new Point((tmp.Width - S.Width) / 2, (tmp.Height - S.Height) / 2);

    g.DrawImage(pic, new Rectangle(P, S));

    return tmp;     //返回构建的新图像
}


//保存图像pic到文件fileName中,指定图像保存格式
public static void SaveToFile(Image pic, string fileName, bool replace, ImageFormat format)    //ImageFormat.Jpeg
{
    //若图像已存在,则删除
    if (System.IO.File.Exists(fileName) && replace)
        System.IO.File.Delete(fileName);

    //若不存在则创建
    if (!System.IO.File.Exists(fileName))
    {
        if (format == null) format = getFormat(fileName);   //根据拓展名获取图像的对应存储类型

        if (format == ImageFormat.MemoryBmp) pic.Save(fileName);
        else pic.Save(fileName, format);                    //按给定格式保存图像
    }
}

//根据文件拓展名,获取对应的存储类型
public static ImageFormat getFormat(string filePath)
{
    ImageFormat format = ImageFormat.MemoryBmp;
    String Ext = System.IO.Path.GetExtension(filePath).ToLower();

    if (Ext.Equals(".png")) format = ImageFormat.Png;
    else if (Ext.Equals(".jpg") || Ext.Equals(".jpeg")) format = ImageFormat.Jpeg;
    else if (Ext.Equals(".bmp")) format = ImageFormat.Bmp;
    else if (Ext.Equals(".gif")) format = ImageFormat.Gif;
    else if (Ext.Equals(".ico")) format = ImageFormat.Icon;
    else if (Ext.Equals(".emf")) format = ImageFormat.Emf;
    else if (Ext.Equals(".exif")) format = ImageFormat.Exif;
    else if (Ext.Equals(".tiff")) format = ImageFormat.Tiff;
    else if (Ext.Equals(".wmf")) format = ImageFormat.Wmf;
    else if (Ext.Equals(".memorybmp")) format = ImageFormat.MemoryBmp;

    return format;
}

[DllImport("user32.dll")]
static extern bool GetCursorInfo(out CURSORINFO pci);

private const Int32 CURSOR_SHOWING = 0x00000001;
[StructLayout(LayoutKind.Sequential)]
struct POINT
{
    public Int32 x;
    public Int32 y;
}

[StructLayout(LayoutKind.Sequential)]
struct CURSORINFO
{
    public Int32 cbSize;
    public Int32 flags;
    public IntPtr hCursor;
    public POINT ptScreenPos;
}

/// <summary>
/// 截取屏幕指定区域为Image,保存到路径savePath下,haveCursor是否包含鼠标
/// </summary>
public static Image getScreen(int x = 0, int y = 0, int width = -1, int height = -1, String savePath = "", bool haveCursor = true)
{
    if (width == -1) width = SystemInformation.VirtualScreen.Width;
    if (height == -1) height = SystemInformation.VirtualScreen.Height;

    Bitmap tmp = new Bitmap(width, height);                 //按指定大小创建位图
    Graphics g = Graphics.FromImage(tmp);                   //从位图创建Graphics对象
    g.CopyFromScreen(x, y, 0, 0, new Size(width, height));  //绘制

    // 绘制鼠标
    if (haveCursor)
    {
        try
        {
            CURSORINFO pci;
            pci.cbSize = Marshal.SizeOf(typeof(CURSORINFO));
            GetCursorInfo(out pci);
            System.Windows.Forms.Cursor cur = new System.Windows.Forms.Cursor(pci.hCursor);
            cur.Draw(g, new Rectangle(pci.ptScreenPos.x, pci.ptScreenPos.y, cur.Size.Width, cur.Size.Height));
        }
        catch (Exception ex) { }    // 若获取鼠标异常则不显示
    }

    //Size halfSize = new Size((int)(tmp.Size.Width * 0.8), (int)(tmp.Size.Height * 0.8));  // 按一半尺寸存储图像
    if (!savePath.Equals("")) saveImage(tmp, tmp.Size, savePath);       // 保存到指定的路径下

    return tmp;     //返回构建的新图像
}

/// <summary>
/// 缩放icon为指定的尺寸,并保存到路径PathName
/// </summary>
public static void saveImage(Image image, Size size, String PathName)
{
    Image tmp = shrinkTo(image, size, false);
    SaveToFile(tmp, PathName, true, null);
}

# endregion



2011-03-04 09:17:00 jiangxinyu 阅读数 63943
  • C#急速入门

    Unity开发,C#绝对是基础中的基础,课程针对纯小白而设计,各种语言细节在课程里均有涉猎,从原理到实战,从底层到算法,你想了解的C#,这里应有尽有,除了讲解,还有练习,你说棒不棒,哈哈,当然如果你是有其他语言基础的同学,课程依然会让你收货满满。来吧,我们进入正题。 C#语言系列课程分为五个部分: 1.C#急速入门 2.C#之面向对象 观看地址:https://edu.csdn.net/course/detail/9447 3.C#高级进阶(期待中……) 4.程序员内功修炼 - 数据结构(C#) 观看地址: https://edu.csdn.net/course/detail/10505 5.Unity百家公司面试题总结  C#部分(期待中……)    #此后新课程更新将在张建飞老师个人账号下发布 敬请关注~~ https://edu.csdn.net/lecturer/2528

    21740 人正在学习 去看看 张建飞

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 original
new Point(100, 100),// destination for upper-right point of original
new Point(0, 0)}; // destination for lower-left point of original
g.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 original
new Point(100, 100),// destination for upper-right point of original
new Point(0, 0)}; // destination for lower-left point of original
g.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 original
new Point(100, 0), // destination for upper-right point of original
new Point(50, 100)};// destination for lower-left point of original
g.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 rectangle
GraphicsUnit.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);

}


//
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CompositingMode
Bitmap 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 window
gForm.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

 

 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。

Bitmap类中我们可以看到这样两个方法:GetPixelint x, int y)和SetPixelint 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7PictureBox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pictureBox1pictureBox6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23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(),CloneRectangle PixelFormat)和CloneRectangleF 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);

 

 

 

 

. 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);
            }
        }

. 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);
            }
        }

. 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");
            }
        }

 

. 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");
            }
        }

.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");
            }
        }

. 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

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++)
                    {
    //
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]];
                }
            }
        }

}
}
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

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GetPixelSetPixel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

 

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 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 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:

  • 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);

}

 

 

 

 

2014-12-01 16:49:02 zhuxiaowei716 阅读数 3690
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