RDJPGCOM(1)                                           RDJPGCOM(1)

NAME
       rdjpgcom - display text comments from a JPEG file

SYNOPSIS
       rdjpgcom [ -verbose ] [ filename ]

DESCRIPTION
       rdjpgcom  reads  the named JPEG/JFIF file, or the standard
       input if no file is named, and prints  any  text  comments
       found in the file on the standard output.

       The  JPEG  standard allows "comment" (COM) blocks to occur
       within a JPEG file.  Although the standard  doesn't  actu-
       ally  define what COM blocks are for, they are widely used
       to hold user-supplied text strings.   This  lets  you  add
       annotations,  titles, index terms, etc to your JPEG files,
       and later retrieve them as text.  COM blocks do not inter-
       fere  with the image stored in the JPEG file.  The maximum
       size of a COM block is 64K, but you can have  as  many  of
       them as you like in one JPEG file.

OPTIONS
       -verbose
              Causes  rdjpgcom  to  also  display  the JPEG image
              dimensions.

       Switch names may be abbreviated, and are not  case  sensi-
       tive.

HINTS
       rdjpgcom  does  not  depend  on the IJG JPEG library.  Its
       source code is intended as an illustration of the  minimum
       amount  of  code required to parse a JPEG file header cor-
       rectly.

       In -verbose mode, rdjpgcom will also attempt to print  the
       contents  of  any  "APP12"  markers as text.  Some digital
       cameras produce APP12 markers  containing  useful  textual
       information.   If you like, you can modify the source code
       to print other APPn marker types as well.

SEE ALSO
       cjpeg(1), djpeg(1), jpegtran(1), wrjpgcom(1)

AUTHOR
       Independent JPEG Group

                         11 October 1997                        1