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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1 .TH WRJPGCOM 1 "15 June 1995"
2 .SH NAME
3 wrjpgcom \- insert text comments into a JPEG file
4 .SH SYNOPSIS
5 .B wrjpgcom
6 [
7 .B \-replace
8 ]
9 [
10 .BI \-comment " text"
11 ]
12 [
13 .BI \-cfile " name"
14 ]
15 [
16 .I filename
17 ]
18 .LP
19 .SH DESCRIPTION
20 .LP
21 .B wrjpgcom
22 reads the named JPEG/JFIF file, or the standard input if no file is named,
23 and generates a new JPEG/JFIF file on standard output. A comment block is
24 added to the file.
25 .PP
26 The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
27 Although the standard doesn't actually define what COM blocks are for, they
28 are widely used to hold user-supplied text strings. This lets you add
29 annotations, titles, index terms, etc to your JPEG files, and later retrieve
30 them as text. COM blocks do not interfere with the image stored in the JPEG
31 file. The maximum size of a COM block is 64K, but you can have as many of
32 them as you like in one JPEG file.
33 .PP
34 .B wrjpgcom
35 adds a COM block, containing text you provide, to a JPEG file.
36 Ordinarily, the COM block is added after any existing COM blocks; but you
37 can delete the old COM blocks if you wish.
38 .SH OPTIONS
39 Switch names may be abbreviated, and are not case sensitive.
40 .TP
41 .B \-replace
42 Delete any existing COM blocks from the file.
43 .TP
44 .BI \-comment " text"
45 Supply text for new COM block on command line.
46 .TP
47 .BI \-cfile " name"
48 Read text for new COM block from named file.
49 .PP
50 If you have only one line of comment text to add, you can provide it on the
51 command line with
52 .BR \-comment .
53 The comment text must be surrounded with quotes so that it is treated as a
54 single argument. Longer comments can be read from a text file.
55 .PP
56 If you give neither
57 .B \-comment
58 nor
59 .BR \-cfile ,
60 then
61 .B wrjpgcom
62 will read the comment text from standard input. (In this case an input image
63 file name MUST be supplied, so that the source JPEG file comes from somewhere
64 else.) You can enter multiple lines, up to 64KB worth. Type an end-of-file
65 indicator (usually control-D) to terminate the comment text entry.
66 .PP
67 .B wrjpgcom
68 will not add a COM block if the provided comment string is empty. Therefore
69 \fB\-replace \-comment ""\fR can be used to delete all COM blocks from a file.
70 .SH EXAMPLES
71 .LP
72 Add a short comment to in.jpg, producing out.jpg:
73 .IP
74 .B wrjpgcom \-c
75 \fI"View of my back yard" in.jpg
76 .B >
77 .I out.jpg
78 .PP
79 Attach a long comment previously stored in comment.txt:
80 .IP
81 .B wrjpgcom
82 .I in.jpg
83 .B <
84 .I comment.txt
85 .B >
86 .I out.jpg
87 .PP
88 or equivalently
89 .IP
90 .B wrjpgcom
91 .B -cfile
92 .I comment.txt
93 .B <
94 .I in.jpg
95 .B >
96 .I out.jpg
97 .SH SEE ALSO
98 .BR cjpeg (1),
99 .BR djpeg (1),
100 .BR jpegtran (1),
101 .BR rdjpgcom (1)
102 .SH AUTHOR
103 Independent JPEG Group