NAME

       rdjpgcom - display text comments from a JPEG file

SYNOPSIS

       rdjpgcom [ -raw ] [ -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  actually  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 interfere 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

       -raw   Normally  rdjpgcom  escapes  non-printable  characters  in  comments,  for security
              reasons.  This option avoids that.

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

       Switch names may be abbreviated, and are not case sensitive.

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 correctly.

       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

                                          02 April 2009                               RDJPGCOM(1)