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