DragonFly On-Line Manual Pages

WRJPGCOM(1)            DragonFly General Commands Manual           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)