RDJPGCOM(1)                                                                                                          RDJPGCOM(1)



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)