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)