com2pgm.c

常好且全面的jpeg图像压缩算法

/*This program is wrote by Fujian Shi([e-mail])*/
/*It can transform the com file to pgm file ,you can watch the picture*/
#include "stddef.h"
#include "stdio.h"
void put_measure(FILE *file,unsigned int val,char  th)
{
  int i=10000,temp,time=0;
  if (th == 0) i /=10; 
  while(1) {
    i/=10;
    temp=val/i;
    if (temp >0)
      time++;
    if(temp>10) {
      printf("Please increase the origin value of i,now it is 10000.\n");
      exit(0);
    }
  if ((time==0) && (temp==0))
     continue;
      putc((char) (temp+48),file);
  if((val-=i*temp)==0)
      break;
  }
}

main(int argc,char *argv[])
{
  #define UCH(x)	((int) (x))
  #define GET_2B(array,offset)  ((unsigned int) UCH(array[offset]) + \
			       (((unsigned int) UCH(array[offset+1])) << 8))
  #define JFREAD(file,buf,sizeofbuf)  \
  ((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
  #define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))
  FILE *file1,*file2;
  char c1;
  unsigned int width,height;
  int c2;
  unsigned char width_height[4];
  if ((file1=fopen(argv[1],"rb"))==NULL)
    printf("the %scan't  be opened",argv[1]);
  if ((file2=fopen(argv[2],"wb+"))==NULL)
    printf("the %scan't  be opened",argv[2]);
  if (! ReadOK(file1, width_height, 4)){
    printf("error when read the head of file1");
    exit(0);
  }
  width=GET_2B(width_height,0);
  height=GET_2B(width_height,2);
  c1=80;
  fputc(c1,file2);
  c1=0x35;
  fputc(c1,file2);
  c1=10;
  fputc(c1,file2);
  /*fputc((char) 48,file2);*/
  put_measure(file2,width,1);
  c1=32;
  fputc(c1,file2);
  /*fputc((char) 48,file2);*/
  put_measure(file2,height,1);
  c1=10;
  fputc(c1,file2);
  put_measure(file2,(unsigned int)255,0);
  fputc((char) (10),file2);
  while ((c2 = getc(file1)) != EOF)
    putc((char) (c2),file2);
  fclose(file1);
  fclose(file2);
  return(0);
}