WRJPGCOM(1)							  WRJPGCOM(1)



NAME
       wrjpgcom - insert text comments into a JPEG file

SYNOPSIS
       wrjpgcom [ -replace ] [ -comment text ] [ -cfile name ] [ filename ]


DESCRIPTION
       wrjpgcom	 reads	the named JPEG/JFIF file, or the standard input if no
       file is named, and generates a new JPEG/JFIF file on standard  output.
       A comment block is added to the file.

       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.

       wrjpgcom adds a COM block, containing text  you	provide,  to  a	 JPEG
       file.   Ordinarily,  the	 COM  block  is	 added after any existing COM
       blocks; but you can delete the old COM blocks if you wish.

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

       -replace
	      Delete any existing COM blocks from the file.

       -comment text
	      Supply text for new COM block on command line.

       -cfile name
	      Read text for new COM block from named file.

       If you have only one line of comment text to add, you can  provide  it
       on  the	command	 line  with  -comment.	The comment text must be sur-
       rounded with quotes so that  it	is  treated  as	 a  single  argument.
       Longer comments can be read from a text file.

       If  you	give neither -comment nor -cfile, then wrjpgcom will read the
       comment text from standard input.  (In this case an input  image	 file
       name  MUST  be supplied, so that the source JPEG file comes from some-
       where else.)  You can enter multiple lines, up to 64KB worth.  Type an
       end-of-file  indicator  (usually	 control-D)  to terminate the comment
       text entry.

       wrjpgcom will not add a COM block if the provided  comment  string  is
       empty.	Therefore  -replace -comment "" can be used to delete all COM
       blocks from a file.

EXAMPLES
       Add a short comment to in.jpg, producing out.jpg:

	      wrjpgcom -c "View of my back yard" in.jpg > out.jpg

       Attach a long comment previously stored in comment.txt:

	      wrjpgcom in.jpg < comment.txt > out.jpg

       or equivalently

	      wrjpgcom -cfile comment.txt < in.jpg > out.jpg

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

AUTHOR
       Independent JPEG Group



				 15 June 1995			  WRJPGCOM(1)

UNIX/Linux commands referenced on this page:

1. file
2. as
3. size