jpayne@68: .TH WRJPGCOM 1 "15 June 1995"
jpayne@68: .SH NAME
jpayne@68: wrjpgcom \- insert text comments into a JPEG file
jpayne@68: .SH SYNOPSIS
jpayne@68: .B wrjpgcom
jpayne@68: [
jpayne@68: .B \-replace
jpayne@68: ]
jpayne@68: [
jpayne@68: .BI \-comment " text"
jpayne@68: ]
jpayne@68: [
jpayne@68: .BI \-cfile " name"
jpayne@68: ]
jpayne@68: [
jpayne@68: .I filename
jpayne@68: ]
jpayne@68: .LP
jpayne@68: .SH DESCRIPTION
jpayne@68: .LP
jpayne@68: .B wrjpgcom
jpayne@68: reads the named JPEG/JFIF file, or the standard input if no file is named,
jpayne@68: and generates a new JPEG/JFIF file on standard output.  A comment block is
jpayne@68: added to the file.
jpayne@68: .PP
jpayne@68: The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
jpayne@68: Although the standard doesn't actually define what COM blocks are for, they
jpayne@68: are widely used to hold user-supplied text strings.  This lets you add
jpayne@68: annotations, titles, index terms, etc to your JPEG files, and later retrieve
jpayne@68: them as text.  COM blocks do not interfere with the image stored in the JPEG
jpayne@68: file.  The maximum size of a COM block is 64K, but you can have as many of
jpayne@68: them as you like in one JPEG file.
jpayne@68: .PP
jpayne@68: .B wrjpgcom
jpayne@68: adds a COM block, containing text you provide, to a JPEG file.
jpayne@68: Ordinarily, the COM block is added after any existing COM blocks; but you
jpayne@68: can delete the old COM blocks if you wish.
jpayne@68: .SH OPTIONS
jpayne@68: Switch names may be abbreviated, and are not case sensitive.
jpayne@68: .TP
jpayne@68: .B \-replace
jpayne@68: Delete any existing COM blocks from the file.
jpayne@68: .TP
jpayne@68: .BI \-comment " text"
jpayne@68: Supply text for new COM block on command line.
jpayne@68: .TP
jpayne@68: .BI \-cfile " name"
jpayne@68: Read text for new COM block from named file.
jpayne@68: .PP
jpayne@68: If you have only one line of comment text to add, you can provide it on the
jpayne@68: command line with
jpayne@68: .BR \-comment .
jpayne@68: The comment text must be surrounded with quotes so that it is treated as a
jpayne@68: single argument.  Longer comments can be read from a text file.
jpayne@68: .PP
jpayne@68: If you give neither
jpayne@68: .B \-comment
jpayne@68: nor
jpayne@68: .BR \-cfile ,
jpayne@68: then
jpayne@68: .B wrjpgcom
jpayne@68: will read the comment text from standard input.  (In this case an input image
jpayne@68: file name MUST be supplied, so that the source JPEG file comes from somewhere
jpayne@68: else.)  You can enter multiple lines, up to 64KB worth.  Type an end-of-file
jpayne@68: indicator (usually control-D) to terminate the comment text entry.
jpayne@68: .PP
jpayne@68: .B wrjpgcom
jpayne@68: will not add a COM block if the provided comment string is empty.  Therefore
jpayne@68: \fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file.
jpayne@68: .SH EXAMPLES
jpayne@68: .LP
jpayne@68: Add a short comment to in.jpg, producing out.jpg:
jpayne@68: .IP
jpayne@68: .B wrjpgcom \-c
jpayne@68: \fI"View of my back yard" in.jpg
jpayne@68: .B >
jpayne@68: .I out.jpg
jpayne@68: .PP
jpayne@68: Attach a long comment previously stored in comment.txt:
jpayne@68: .IP
jpayne@68: .B wrjpgcom
jpayne@68: .I in.jpg
jpayne@68: .B <
jpayne@68: .I comment.txt
jpayne@68: .B >
jpayne@68: .I out.jpg
jpayne@68: .PP
jpayne@68: or equivalently
jpayne@68: .IP
jpayne@68: .B wrjpgcom
jpayne@68: .B -cfile
jpayne@68: .I comment.txt
jpayne@68: .B <
jpayne@68: .I in.jpg
jpayne@68: .B >
jpayne@68: .I out.jpg
jpayne@68: .SH SEE ALSO
jpayne@68: .BR cjpeg (1),
jpayne@68: .BR djpeg (1),
jpayne@68: .BR jpegtran (1),
jpayne@68: .BR rdjpgcom (1)
jpayne@68: .SH AUTHOR
jpayne@68: Independent JPEG Group