source: rtems-graphics-toolkit/jpeg-8d/rdjpgcom.1 @ 86b99f7

Last change on this file since 86b99f7 was 86b99f7, checked in by Alexandru-Sever Horin <alex.sever.h@…>, on Aug 1, 2012 at 10:40:32 PM

Added jpeg-8d version. Made modifications to compile for RTEMS, without man or binaries

  • Property mode set to 100644
File size: 1.7 KB
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1.TH RDJPGCOM 1 "02 April 2009"
2.SH NAME
3rdjpgcom \- display text comments from a JPEG file
4.SH SYNOPSIS
5.B rdjpgcom
6[
7.B \-raw
8]
9[
10.B \-verbose
11]
12[
13.I filename
14]
15.LP
16.SH DESCRIPTION
17.LP
18.B rdjpgcom
19reads the named JPEG/JFIF file, or the standard input if no file is named,
20and prints any text comments found in the file on the standard output.
21.PP
22The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
23Although the standard doesn't actually define what COM blocks are for, they
24are widely used to hold user-supplied text strings.  This lets you add
25annotations, titles, index terms, etc to your JPEG files, and later retrieve
26them as text.  COM blocks do not interfere with the image stored in the JPEG
27file.  The maximum size of a COM block is 64K, but you can have as many of
28them as you like in one JPEG file.
29.SH OPTIONS
30.TP
31.B \-raw
32Normally
33.B rdjpgcom
34escapes non-printable characters in comments, for security reasons.
35This option avoids that.
36.PP
37.B \-verbose
38Causes
39.B rdjpgcom
40to also display the JPEG image dimensions.
41.PP
42Switch names may be abbreviated, and are not case sensitive.
43.SH HINTS
44.B rdjpgcom
45does not depend on the IJG JPEG library.  Its source code is intended as an
46illustration of the minimum amount of code required to parse a JPEG file
47header correctly.
48.PP
49In
50.B \-verbose
51mode,
52.B rdjpgcom
53will also attempt to print the contents of any "APP12" markers as text.
54Some digital cameras produce APP12 markers containing useful textual
55information.  If you like, you can modify the source code to print
56other APPn marker types as well.
57.SH SEE ALSO
58.BR cjpeg (1),
59.BR djpeg (1),
60.BR jpegtran (1),
61.BR wrjpgcom (1)
62.SH AUTHOR
63Independent JPEG Group
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