| 1 | .TH WRJPGCOM 1 "15 June 1995"
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| 2 | .SH NAME
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| 3 | wrjpgcom \- insert text comments into a JPEG file
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| 4 | .SH SYNOPSIS
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| 5 | .B wrjpgcom
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| 6 | [
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| 7 | .B \-replace
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| 8 | ]
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| 9 | [
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| 10 | .BI \-comment " text"
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| 11 | ]
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| 12 | [
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| 13 | .BI \-cfile " name"
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| 14 | ]
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| 15 | [
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| 16 | .I filename
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| 17 | ]
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| 18 | .LP
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| 19 | .SH DESCRIPTION
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| 20 | .LP
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| 21 | .B wrjpgcom
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| 22 | reads the named JPEG/JFIF file, or the standard input if no file is named,
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| 23 | and generates a new JPEG/JFIF file on standard output. A comment block is
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| 24 | added to the file.
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| 25 | .PP
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| 26 | The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
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| 27 | Although the standard doesn't actually define what COM blocks are for, they
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| 28 | are widely used to hold user-supplied text strings. This lets you add
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| 29 | annotations, titles, index terms, etc to your JPEG files, and later retrieve
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| 30 | them as text. COM blocks do not interfere with the image stored in the JPEG
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| 31 | file. The maximum size of a COM block is 64K, but you can have as many of
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| 32 | them as you like in one JPEG file.
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| 33 | .PP
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| 34 | .B wrjpgcom
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| 35 | adds a COM block, containing text you provide, to a JPEG file.
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| 36 | Ordinarily, the COM block is added after any existing COM blocks; but you
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| 37 | can delete the old COM blocks if you wish.
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| 38 | .SH OPTIONS
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| 39 | Switch names may be abbreviated, and are not case sensitive.
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| 40 | .TP
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| 41 | .B \-replace
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| 42 | Delete any existing COM blocks from the file.
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| 43 | .TP
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| 44 | .BI \-comment " text"
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| 45 | Supply text for new COM block on command line.
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| 46 | .TP
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| 47 | .BI \-cfile " name"
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| 48 | Read text for new COM block from named file.
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| 49 | .PP
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| 50 | If you have only one line of comment text to add, you can provide it on the
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| 51 | command line with
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| 52 | .BR \-comment .
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| 53 | The comment text must be surrounded with quotes so that it is treated as a
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| 54 | single argument. Longer comments can be read from a text file.
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| 55 | .PP
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| 56 | If you give neither
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| 57 | .B \-comment
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| 58 | nor
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| 59 | .BR \-cfile ,
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| 60 | then
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| 61 | .B wrjpgcom
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| 62 | will read the comment text from standard input. (In this case an input image
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| 63 | file name MUST be supplied, so that the source JPEG file comes from somewhere
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| 64 | else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file
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| 65 | indicator (usually control-D) to terminate the comment text entry.
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| 66 | .PP
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| 67 | .B wrjpgcom
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| 68 | will not add a COM block if the provided comment string is empty. Therefore
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| 69 | \fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file.
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| 70 | .SH EXAMPLES
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| 71 | .LP
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| 72 | Add a short comment to in.jpg, producing out.jpg:
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| 73 | .IP
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| 74 | .B wrjpgcom \-c
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| 75 | \fI"View of my back yard" in.jpg
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| 76 | .B >
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| 77 | .I out.jpg
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| 78 | .PP
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| 79 | Attach a long comment previously stored in comment.txt:
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| 80 | .IP
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| 81 | .B wrjpgcom
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| 82 | .I in.jpg
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| 83 | .B <
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| 84 | .I comment.txt
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| 85 | .B >
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| 86 | .I out.jpg
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| 87 | .PP
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| 88 | or equivalently
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| 89 | .IP
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| 90 | .B wrjpgcom
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| 91 | .B -cfile
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| 92 | .I comment.txt
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| 93 | .B <
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| 94 | .I in.jpg
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| 95 | .B >
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| 96 | .I out.jpg
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| 97 | .SH SEE ALSO
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| 98 | .BR cjpeg (1),
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| 99 | .BR djpeg (1),
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| 100 | .BR jpegtran (1),
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| 101 | .BR rdjpgcom (1)
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| 102 | .SH AUTHOR
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| 103 | Independent JPEG Group
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