在C ++中使用3X3低通滤波器对.pgm图像进行卷积

我试图用C ++编写一个程序，该程序具有以下3个功能：（i）read_pgm_image（）-从文件中读取.pgm格式的图像；（ii）convolve（）-使用3X3低通滤波器对图像进行卷积；（iii）write_pgm_image（）-将图像数据写回到单独的文件中

这是我的代码：

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

void read_pgm_image(char name[]);
void convolve(int img[][256], int M, int N, int img_intensity);
void write_pgm_image(char name[], int img[256][256], int img_data[]);

int main()
{   read_pgm_image("lenna2.pgm");

    getchar();
    return 0;
}

void read_pgm_image(char name[])
{   string magic, creator_info;
    int img_intensity, M, N;
    ifstream file(name, ios::binary);
    if(file.is_open())
    {   cout<<"File successfully opened! \n\n";
        cout<<"Reading the file...\n";
        cout<<"Name of the file:\t"<<name<<'\n';

        getline(file,magic); // get the magic number

        getline(file,creator_info); // get the creator information

        file>>M; // get width of the image
        cout<<"Width of the Image:\t"<<M<<'\n';

        file>>N; // get length of the image
        cout<<"Length of the Image:\t"<<N<<'\n';

        file>>img_intensity; // get the image intensity
        cout<<"Maximum Intensity:\t"<<img_intensity<<'\n'; 

        int img[256][256]; // create an array to store image data
        for(int i=0; i<N; i++)
        {   for(int j=0; j<M; j++)
            {   file.read((char*)&img[i][j],sizeof(int));
            }
        }
        file.close();

        convolve(img, M, N, img_intensity); // Calling the Convolve function
    }
    else
    {   cout<<"Error in opening image!";
        file.close();
    }
}



void convolve(int img[256][256], int M, int N, int img_intensity)
{   int con_img[256][256], sum=0, img_data[3]={M,N,img_intensity};

    for(int i=0; i<N; i++)
    {   for(int j=0; j<M; j++)
        {   con_img[i][j]=img[i][j];
        }
    }

    for(int i=1; i<(N-1); i++)
{   for(int j=1; j<(M-1); j++)
    {   for(int k=(i-1); k<(i+1); k++)
        {   for(int l=(j-1); l<(j+1); l++)
            {   sum = sum + img[k][l];
            }
        }
        con_img[i][j] = sum/9;
        sum=0;
    }
}

write_pgm_image("image_convolve.pgm", con_img, img_data);
}



void write_pgm_image(char name[], int img[256][256], int img_data[3])
{ cout<<"\nCreating image file...\n";

  ofstream file(name,ios::binary);

  if(file.is_open())
  {   cout<<"File successfully created!\n";
      cout<<"Writing image data...\n";

      file<<"P5\n"<<img_data[0]<<' '<<img_data[1]<<' '<<img_data[2]; //Writing P5, image width, image length and maximum intensity

      cout<<"Image data written!\n";

      for(int i=0; i<img_data[1]; i++)  //Write image data to the file
        {   for(int j=0; j<img_data[0]; j++)
            {   file.write((char*)&(img[i][j]), sizeof(int));
            }
        }
      cout<<"Image pixel info written!\n";
      file.close();
  }
  else
  { cout <<"Error in creating file!";
    file.close();
  }
}

convolve（）函数似乎存在一些问题。理想情况下，我应该获得输入图像的模糊版本（我无法上传）。但是我却得到了一个垃圾图像。

非常感谢您的任何帮助...谢谢。