Question

我想读取一个PGM文件（没有#views）并将图像数据（矩阵）导出到一个新的文本文件。到目前为止，我确实设法编写了代码，但我认为不是很好。我的问题是，当我将矩阵从内存中打印到文本文件时，它会给我一些零的行。当我想从内存中打印矩阵时，我会这样做。

有代码：

#include<stdio.h>
#include<stdlib.h>

int main(){
int i,j;
FILE *fd;
FILE *fdd;

//Extract the file info from header 
char type;
int row=0,col=0,depht=0,a=0;
fd=fopen("file.pgm","rb");
fscanf(fd,"%s %d %d %d",&type,&row,&col,&depht);

//Malloc
int** sudo=(int **)malloc(row*sizeof(int *));
if ( sudo != NULL){
   for (k=0; k<row ;k++){
       sudo[k] =(int*) calloc (col,sizeof (int));
         }
       }

//Read the image data from the rest of the file
for(i=0;i<row;i++){
   for(j=0;j<col;j++){
        fscanf(fd,"%c ", &sudo[i][j]);
         }
      }
fclose(fd);

//
printf("Header:\nfile type: %s\nrow: %d\ncol: %d\ndepht: %d\n",&type,row,col,depht);

//Copy the matrix from memory to a new file
fdd=fopen("matrice.txt","wb");

for(i=0;i<row;i++){
   for(j=0;j<col;j++){
      fprintf(fdd,"%d ",sudo[i][j]);
      }
    fprintf(fdd,"\n");
 }

 free(sudo);
 fclose(fdd);
 return 0;
}

有什么想法吗？

Answer 1

这是.pgm文件的格式，如下所示：

<http://netpbm.sourceforge.net/doc/pgm.html>:

A PGM file consists of a sequence of one or more PGM images. 
There are no data, delimiters, or padding before, after, or between images.

Each PGM image consists of the following:

    A "magic number" for identifying the file type. 
        A pgm image's magic number is the two characters "P5".
    Whitespace (blanks, TABs, CRs, LFs).
    A width, formatted as ASCII characters in decimal.
    Whitespace.
    A height, again in ASCII decimal.
    Whitespace.
    The maximum gray value (Maxval), again in ASCII decimal. 
        Must be less than 65536, and more than zero.
    A single whitespace character (usually a newline).
    A raster of Height rows, in order from top to bottom. 
       Each row consists of Width gray values, in order from left to right. 
    Each gray value is a number from 0 through Maxval, with 0 being black and Maxval being white. 
    Each gray value is represented in pure binary by either 1 or 2 bytes. 
    If the Maxval is less than 256, it is 1 byte. Otherwise, it is 2 bytes. 
    The most significant byte is first.

    A row of an image is horizontal. 
    A column is vertical. 
    The pixels in the image are square and contiguous.

    Each gray value is a number proportional to the intensity of the pixel, 
    adjusted by the ITU-R Recommendation BT.709 gamma transfer function.  
    (That transfer function specifies a gamma number of 2.2 and has a linear section for small intensities). 
    A value of zero is therefore black. 
    A value of Maxval represents CIE D65 white 
       and the most intense value in the image 
       and any other image to which the image might be compared.

    Note that a common variation on the PGM format 
       is to have the gray value be "linear," 
       i.e. as specified above except without the gamma adjustment.
       `pnmgamma` takes such a PGM variant as input and produces a true PGM as output.

    In the transparency mask variation on PGM, the value represents opaqueness. It is proportional to the fraction of intensity of a pixel that would show in place of an underlying pixel. So what normally means white represents total opaqueness and what normally means black represents total transparency. In between, you would compute the intensity of a composite pixel of an "under" and "over" pixel as under * (1-(alpha/alpha_maxval)) + over * (alpha/alpha_maxval). 
    Note that there is no gamma transfer function in the transparency mask. 

Strings starting with "#" may be comments, the same as with PBM.

Note that you can use `pamdepth` to convert between a the format with 1 byte per gray value and the one with 2 bytes per gray value.

All characters referred to herein are encoded in ASCII. 
"newline" refers to the character known in ASCII as Line Feed or LF. 
A "white space" character is space, CR, LF, TAB, VT, or FF 
    (I.e. what the ANSI standard C isspace() function calls white space).

从PGM文件C读取矩阵时出现问题

1 个答案: