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 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
       -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 mark-
       ers containing useful textual information.  If you like, you can	 mod-
       ify 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			  RDJPGCOM(1)

UNIX/Linux commands referenced on this page:

1. display
2. file
3. as
4. size