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

                                                13 September 2013                                    RDJPGCOM(1)