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[ASP.net教程]C# 内存法图像处理


内存法通过把图像储存在内存中进行处理,效率大大高于GetPixel方法,安全性高于指针法。

笔者当初写图像处理的时候发现网上多是用GetPixel方法实现,提到内存法的时候也没有具体实现,所以笔者在这里具体实现一下- -,望指正。

首先讲一下用到的一些方法。

1.LockBits和UnlockBits:使用 LockBits 方法,可在系统内存中锁定现有的位图,以便通过编程方式进行更改,每调用LockBits之后都应该调用一次UnlockBits。

2.Scan0:图像的第一个字节地址。

3.Stride:步幅,扫描宽度,形象的说就是一行的长度。

4.PixelFormat:数据的实际像素格式。

给出原图:

 

一、灰度

对每个像素点进行加权平均,(方法不唯一)。

    /// <summary>    /// 灰化实现方法    /// </summary>    void Image_Ashing()    {      if (pbshowbox.Image != null)      {        int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb);        Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);        unsafe        {          byte* pin = (byte*)(oldData.Scan0.ToPointer());          byte* pout = (byte*)(newData.Scan0.ToPointer());          for (int y = 0; y < oldData.Height; y++)          {            for (int x = 0; x < oldData.Width; x++)            {              byte Result = (byte)(pin[0] * 0.1 + pin[1] * 0.2 + pin[2] * 0.7);//加权平均实现灰化              pout[0] = (byte)(Result);              pout[1] = (byte)(Result);              pout[2] = (byte)(Result);              pin = pin + 3;              pout = pout + 3;            }            pin += oldData.Stride - oldData.Width * 3;            pout += newData.Stride - newData.Width * 3;          }          bitmap.UnlockBits(newData);          MyBitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

二、柔化

像素点与周围像素点差别较大时取平均值。

    /// <summary>    /// 柔化实现方法    /// </summary>    void Image_Soften()    {      if (pbshowbox.Image != null)      {        int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format32bppRgb);        Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb);        unsafe        {          byte* pin = (byte*)(oldData.Scan0.ToPointer());          byte* pout = (byte*)(newData.Scan0.ToPointer());          //高斯模板          int[] Gauss = { 1, 2, 1, 2, 4, 2, 1, 2, 1 };          for (int i = 1; i < Width - 1; i++)          {            for (int j = 1; j < Height - 1; j++)            {              int r = 0, g = 0, b = 0;              int Index = 0;              for (int col = -1; col <= 1; col++)              {                for (int row = -1; row <= 1; row++)                {                  int off = ((j + row) * (Width) + (i + col)) * 4;                  r += pin[off + 0] * Gauss[Index];                  g += pin[off + 1] * Gauss[Index];                  b += pin[off + 2] * Gauss[Index];                  Index++;                }              }              r /= 16;              g /= 16;              b /= 16;              //处理颜色值溢出              if (r < 0) r = 0;              if (r > 255) r = 255;              if (g < 0) g = 0;              if (g > 255) g = 255;              if (b < 0) b = 0;              if (b > 255) b = 255;              int off2 = (j * Width + i) * 4;              pout[off2 + 0] = (byte)r;              pout[off2 + 1] = (byte)g;              pout[off2 + 2] = (byte)b;            }          }          bitmap.UnlockBits(newData);          MyBitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

三、锐化

突出显示颜色值大的像素点。

    /// <summary>    /// 锐化实现方法,显示数值最大像素点    /// </summary>    void Image_Sharpen()    {      if (this.pbshowbox.Image != null)      {        int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format32bppRgb);        Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb);        unsafe        {          byte* pin = (byte*)(oldData.Scan0.ToPointer());          byte* pout = (byte*)(newData.Scan0.ToPointer());          //拉普拉斯模板          int[] Laplacian = { -1, -1, -1, -1, 9, -1, -1, -1, -1 };          for (int i = 1; i < Width - 1; i++)          {            for (int j = 1; j < Height - 1; j++)            {              int r = 0, g = 0, b = 0;              int Index = 0;              for (int col = -1; col <= 1; col++)              {                for (int row = -1; row <= 1; row++)                {                  int off = ((j + row) * (Width) + (i + col)) * 4;                  r += pin[off + 0] * Laplacian[Index];                  g += pin[off + 1] * Laplacian[Index];                  b += pin[off + 2] * Laplacian[Index];                  Index++;                }              }              if (r < 0) r = 0;              if (r > 255) r = 255;              if (g < 0) g = 0;              if (g > 255) g = 255;              if (b < 0) b = 0;              if (b > 255) b = 255;              int off2 = (j * Width + i) * 4;              pout[off2 + 0] = (byte)r;              pout[off2 + 1] = (byte)g;              pout[off2 + 2] = (byte)b;            }          }          bitmap.UnlockBits(newData);          MyBitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

四、浮雕

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。

    /// <summary>    /// 浮雕实现方法    /// </summary>    void Image_Relief()    {      if (this.pbshowbox.Image != null)      {                int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb);        Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);        unsafe        {          byte* pin_1 = (byte*)(oldData.Scan0.ToPointer());          byte* pin_2 = pin_1 + (oldData.Stride);                  byte* pout = (byte*)(newData.Scan0.ToPointer());          for (int y = 0; y < oldData.Height - 1; y++)          {            for (int x = 0; x < oldData.Width; x++)            {                            int b = (int)pin_1[0] - (int)pin_2[0] + 128;              int g = (int)pin_1[1] - (int)pin_2[1] + 128;              int r = (int)pin_1[2] - (int)pin_2[2] + 128;              if (r < 0) r = 0;              if (r > 255) r = 255;              if (g < 0) g = 0;              if (g > 255) g = 255;              if (b < 0) b = 0;              if (b > 255) b = 255;              pout[0] = (byte)(b);              pout[1] = (byte)(g);              pout[2] = (byte)(r);              pin_1 = pin_1 + 3;              pin_2 = pin_2 + 3;              pout = pout + 3;                         }            pin_1 += oldData.Stride - oldData.Width * 3;            pin_2 += oldData.Stride - oldData.Width * 3;            pout += newData.Stride - newData.Width * 3;          }          bitmap.UnlockBits(newData);          MyBitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

五、底片

颜色值取反。

    /// <summary>    /// 底片实现方法    /// </summary>    void Image_Negative()    {      if (pbshowbox.Image != null)      {        int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb);        Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);        unsafe        {          byte* pin = (byte*)(oldData.Scan0.ToPointer());          byte* pout = (byte*)(newData.Scan0.ToPointer());          for (int y = 0; y < oldData.Height; y++)          {            for (int x = 0; x < oldData.Width; x++)            {              pout[0] = (byte)(255 - pin[0]);              pout[1] = (byte)(255 - pin[1]);              pout[2] = (byte)(255 - pin[2]);              pin = pin + 3;              pout = pout + 3;            }            pin += oldData.Stride - oldData.Width * 3;            pout += newData.Stride - newData.Width * 3;          }          bitmap.UnlockBits(newData);          MyBitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

六、积木

低像素置0,高像素置255。

    /// <summary>    /// 积木实现方法    /// </summary>    private void Image_Block()    {      if (this.pbshowbox.Image != null)      {        int Height = this.pbshowbox.Image.Height;        int Width = this.pbshowbox.Image.Width;        Bitmap bitmap = new Bitmap(Width, Height);        Bitmap Mybitmap = (Bitmap)this.pbshowbox.Image;        BitmapData oldData = Mybitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);        BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);        unsafe        {          byte* pin = (byte*)(oldData.Scan0.ToPointer());          byte* pout = (byte*)(newData.Scan0.ToPointer());          for (int y = 0; y < oldData.Height; y++)          {            for (int x = 0; x < oldData.Width; x++)            {              int avg = (pin[0] + pin[1] + pin[2]) / 3;              if (avg > 128)              {                pout[0] = 255;                pout[1] = 255;                pout[2] = 255;              }              else              {                pout[0] = 0;                pout[1] = 0;                pout[2] = 0;              }              pin = pin + 3;              pout = pout + 3;            }            pin = pin + oldData.Stride - oldData.Width * 3;            pout = pout + newData.Stride - newData.Width * 3;          }          bitmap.UnlockBits(newData);          Mybitmap.UnlockBits(oldData);          this.pbshowbox.Image = bitmap;        }      }      else      {        MessageBox.Show("请先打开一张图片!");      }    }

有些图片效果看起来不明显是因为笔者把图缩小了,其实效果挺明显的- -。