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 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  sur-
       rounded 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)