wrjpgcom(1)

WRJPGCOM(1)              USER COMMANDS                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 multi-
     ple lines, up to 64KB worth.  Type an end-of-file  indicator
     (usually control-D) to terminate the comment text entry.

                    Last change: 15 June 1995                   1

WRJPGCOM(1)              USER COMMANDS                WRJPGCOM(1)

     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

                    Last change: 15 June 1995                   2