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- WRJPGCOM(1) WRJPGCOM(1)
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- NAME
- wrjpgcom - insert text comments into a JPEG file
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- SYNOPSIS
- wrjpgcom [ -replace ] [ -comment text ] [ -cfile name ] [
- filename ]
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- 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.
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- The JPEG standard allows "comment" (COM) blocks to occur
- within a JPEG file. Although the standard doesn't actu
- ally 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 inter
- fere 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.
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- 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.
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- OPTIONS
- Switch names may be abbreviated, and are not case sensi
- tive.
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- -replace
- Delete any existing COM blocks from the file.
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- -comment text
- Supply text for new COM block on command line.
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- -cfile name
- Read text for new COM block from named file.
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- 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.
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- 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
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- 15 June 1995 1
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- WRJPGCOM(1) WRJPGCOM(1)
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- comment text entry.
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- 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.
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- EXAMPLES
- Add a short comment to in.jpg, producing out.jpg:
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- wrjpgcom -c "View of my back yard" in.jpg > out.jpg
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- Attach a long comment previously stored in comment.txt:
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- wrjpgcom in.jpg < comment.txt > out.jpg
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- or equivalently
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- wrjpgcom -cfile comment.txt < in.jpg > out.jpg
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- SEE ALSO
- cjpeg(1), djpeg(1), jpegtran(1), rdjpgcom(1)
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- AUTHOR
- Independent JPEG Group
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- 15 June 1995 2
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