C语言实现对bmp格式图片打码

<span style="font-size:14px;">#include<stdio.h> 
#include<stdlib.h> 
#include<string.h> 
#include<unistd.h> 
#include<errno.h> 
#include<sys/types.h> 
#include<sys/stat.h> 
#include<fcntl.h> 
 
 
#define WIDTH  1024 
#define HEIGHT 768 
#define BPP 24 
#define BYTES  (BPP / 8) 
#define HEADER 54  
 
int main(int argc,char* argv[]) 
{ 
  int xoff,yoff,width,height; 
  int fd; 
  int i,j,k; 
  int offset; 
  unsigned char pix[BYTES];   
 
 
   
 
 
  if(argc!=6) 
  { 
    printf("Usage: %s filename xoff yoff width height\n",argv[0]); 
    exit(EXIT_FAILURE); 
  } 
   
  xoff=atoi(argv[2]); 
  yoff=atoi(argv[3]); 
  width=atoi(argv[4]); 
  height=atoi(argv[5]); 
 
 
  xoff=HEIGHT -xoff; 
  yoff=WIDTH - yoff; 
   
   
 
 
  fd=open(argv[1],O_WRONLY); 
  if(fd==-1) 
  { 
    perror("open"); 
    exit(EXIT_FAILURE); 
  } 
 
 
  for(i=xoff;i > xoff - height;i--) 
  { 
    for(j=yoff;j > yoff - width;j--) 
    { 
      offset = HEADER + (i * WIDTH -j )*BYTES; 
      lseek(fd, offset, SEEK_SET); 
      for(k=0; k<BYTES; k++) 
      { 
        pix[j] = random(); 
        write(fd ,&pix[j] ,1); 
      } 
    } 
  } 
  close(fd); 
  return 0; 
}</span>