使用平均内核的图像处理

Question

我一直在研究一个代码，它将图像转化为灰度，然后根据按下哪个按钮进行图像处理。当按下一个按钮（例如，平均3x3，Prewitt 5x5）时，它将调用2D乘法函数，该函数会在灰度图像上循环，同时循环遍历内核，并添加矩阵中的所有值。如果任何值超过255，则将其设置为255.然后在临时位图变量上使用SetPixel，最终将其置于picturebox中。当我运行该程序时，我选择了一个图像并将其显示（作为灰度），但是在选择其中一个过滤器后，程序冻结了大约30秒，然后没有任何更改，也没有应用过滤器。我试过调试，我似乎无法找到问题所在！

编辑：。在最初的问题已经解决了（我不得不刷新PictureBox的新图像的正确显示 但我在这里面临的另一问题与问候的普鲁伊特内核

我得到这个错误 “附加信息：'-6'的值对于'红'无效，'红'应该大于或等于0且小于或等于255.”

我不知道该怎么办在我的代码中更改以解决此问题。

初始化：

public partial class Form1 : Form 
{ 
    private Image img; 
    Bitmap grayscaleimage; 
    double[][] AVGKernel = new double[11][]; 
    double[][] PrewittKernel = new double[11][]; 
    int[] AVGKernal1DH = new int[11]; 
    int[] AVGKernal1DV = new int[11]; 

    Bitmap tempBitmap; 

    public Form1() 
    { 
     InitializeComponent(); 
     for (int i = 0; i < 11; i++) 
     { 
      AVGKernel[i] = new double[11]; 
      PrewittKernel[i] = new double[11]; 
      for (int j = 0; j < 11; j++) 
      { 
       AVGKernel[i][j] = 0; 
       PrewittKernel[i][j] = 0; 
       AVGKernal1DH[j] = 0; 
       AVGKernal1DV[j] = 0; 
      } 
     } 
} 

开放按钮并转动图像为灰度：

private void OpenImageButton(object sender, EventArgs e) 
    { 
     OpenFileDialog openFileDialog = new OpenFileDialog(); 
     if (openFileDialog.ShowDialog() == DialogResult.OK) 
     { 
      this.img = Image.FromFile(openFileDialog.FileName); 

      grayscaleimage = new Bitmap(img); 
      int rgb; 
      Color c; 

      for (int y = 0; y < grayscaleimage.Height; y++) 
       for (int x = 0; x < grayscaleimage.Width; x++) 
       { 
        c = grayscaleimage.GetPixel(x, y); 
        rgb = (int)((c.R + c.G + c.B)/3); 
        grayscaleimage.SetPixel(x, y, Color.FromArgb(rgb, rgb, rgb)); 
       } 
      this.pictureBox1.BackgroundImage = grayscaleimage; 
      pictureBox1.BackgroundImageLayout = ImageLayout.Zoom; 
     } 
    } 

可用的许多按钮的一个示例：

private void button5_Click(object sender, EventArgs e) 
    { 
     AVGKernel[0][0] = 1; AVGKernel[0][1] = 1; AVGKernel[0][2] = 1; AVGKernel[0][3] = 1; AVGKernel[0][4] = 1; 
     AVGKernel[1][0] = 1; AVGKernel[1][1] = 1; AVGKernel[1][2] = 1; AVGKernel[1][3] = 1; AVGKernel[1][4] = 1; 
     AVGKernel[2][0] = 1; AVGKernel[2][1] = 1; AVGKernel[2][2] = 1; AVGKernel[2][3] = 1; AVGKernel[2][4] = 1; 
     AVGKernel[3][0] = 1; AVGKernel[3][1] = 1; AVGKernel[3][2] = 1; AVGKernel[3][3] = 1; AVGKernel[3][4] = 1; 
     AVGKernel[4][0] = 1; AVGKernel[4][1] = 1; AVGKernel[4][2] = 1; AVGKernel[4][3] = 1; AVGKernel[4][4] = 1; 

     kernal2DMultiplication(AVGKernel, 5); 
     this.pictureBox1.BackgroundImage = tempBitmap; 

    } 

Prewitt算子的5×5内核

private void button13_Click(object sender, EventArgs e) 
    { 
     PrewittKernel[0][0] = 2; PrewittKernel[0][1] = 1; PrewittKernel[0][2] = 0; PrewittKernel[0][3] = -1; PrewittKernel[0][4] = -2; 
     PrewittKernel[1][0] = 2; PrewittKernel[1][1] = 1; PrewittKernel[1][2] = 0; PrewittKernel[1][3] = -1; PrewittKernel[1][4] = -2; 
     PrewittKernel[2][0] = 2; PrewittKernel[2][1] = 1; PrewittKernel[2][2] = 0; PrewittKernel[2][3] = -1; PrewittKernel[2][4] = -2; 
     PrewittKernel[3][0] = 2; PrewittKernel[3][1] = 1; PrewittKernel[3][2] = 0; PrewittKernel[3][3] = -1; PrewittKernel[3][4] = -2; 
     PrewittKernel[4][0] = 2; PrewittKernel[4][1] = 1; PrewittKernel[4][2] = 0; PrewittKernel[4][3] = -1; PrewittKernel[4][4] = -2; 

     kernal2DMultiplication(PrewittKernel, 5); 
     this.pictureBox1.BackgroundImage = tempBitmap; 
     this.pictureBox1.Refresh(); 
    } 

和最后，该函数被调用：

private void kernal2DMultiplication(double[][] kernel, int size) 
    { 
     tempBitmap = grayscaleimage; 
     double nrgb = 0; 

     for (int i = 0; i < grayscaleimage.Width - size/2; i++) 
     { 
      for (int j = 0; j < grayscaleimage.Height - size/2; j++) 
      { 
       if (i >= size/2 && j >= size/2) 
       { 
        for (int k = 0; k < size; k++) 
         for (int l = 0; l < size; l++) 

          nrgb += grayscaleimage.GetPixel(i + k - (size/2), j + l - (size/2)).R * kernel[k][l]; 
          nrgb = nrgb/(size * size); 

        if (nrgb > 255) 
         nrgb = 255; 

        tempBitmap.SetPixel(i, j, Color.FromArgb((int)nrgb, (int)nrgb, (int)nrgb)); 

       } 

      } 

     } 
    } 

Answer 1

的问题是，要修改的BackgroundImage位就地而不是复制，修改副本，然后设定复印的BackgroundImage：

this.pictureBox1.BackgroundImage = grayscaleimage; // initially 

    tempBitmap = grayscaleimage; 

    // Make changes to tempBitmap 

    this.pictureBox1.BackgroundImage = tempBitmap; // actually still the same pointer 

的BackgroundImage二传手不是在这种情况下强制重绘控件。要强制这个自己，叫Refresh()：

this.pictureBox1.Refresh(); 

要改良剂的性能，可考虑使用到LockBits单个呼叫更换多次调用SetPixel。见例如here。