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 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)