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 com-
    ments 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  some-
    where 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