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  surrounded  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
       somewhere 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)