Legacy ImageMagick Discussions Archive

fmw42 wrote:try searching google for "unix command line jpg reader" and see if you find anything useful

snibgo wrote:Have you looked at the first 4 (or whatever) magic bytes? Maybe that's all that is wrong. If so, a simple C program could fix it.

<magic name="JPEG" offset="0" target="\377\330\377"/>

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

int main (int argc, char *argv [])
{
  // Strip the first 21 bytes

  FILE * fhin = fopen ("imgfoo.jpg", "rb");
  FILE * fhout = fopen ("imgfoofixed.jpg", "wb");

  char c;
  int i;
  for (i = 0; i < 21; i++) {
    fread (&c, 1, 1, fhin);
  }
  while (fread (&c, 1, 1, fhin)) {
    fwrite (&c, 1, 1, fhout);
  }
  fclose (fhout);
  fclose (fhin);

  return (0);
}

snibgo wrote:imgfoofixed.jpg is now readable by IM and Gimp.

snibgo wrote: it seems imgfoo contains 21 spurious bytes at the start. These can be stripped by a simple C program (or perhaps some shell tool).