WRJPGCOM(1) - man - phpman

WRJPGCOM(1)                            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 gen‐
       erates 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 stan‐
       dard 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  -re‐‐
       place -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)