You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
64 lines
1.7 KiB
64 lines
1.7 KiB
5 years ago
|
.TH RDJPGCOM 1 "02 April 2009"
|
||
|
.SH NAME
|
||
|
rdjpgcom \- display text comments from a JPEG file
|
||
|
.SH SYNOPSIS
|
||
|
.B rdjpgcom
|
||
|
[
|
||
|
.B \-raw
|
||
|
]
|
||
|
[
|
||
|
.B \-verbose
|
||
|
]
|
||
|
[
|
||
|
.I filename
|
||
|
]
|
||
|
.LP
|
||
|
.SH DESCRIPTION
|
||
|
.LP
|
||
|
.B rdjpgcom
|
||
|
reads the named JPEG/JFIF file, or the standard input if no file is named,
|
||
|
and prints any text comments found in the file on the standard output.
|
||
|
.PP
|
||
|
The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
|
||
|
Although the standard doesn't actually 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 interfere 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.
|
||
|
.SH OPTIONS
|
||
|
.TP
|
||
|
.B \-raw
|
||
|
Normally
|
||
|
.B rdjpgcom
|
||
|
escapes non-printable characters in comments, for security reasons.
|
||
|
This option avoids that.
|
||
|
.PP
|
||
|
.B \-verbose
|
||
|
Causes
|
||
|
.B rdjpgcom
|
||
|
to also display the JPEG image dimensions.
|
||
|
.PP
|
||
|
Switch names may be abbreviated, and are not case sensitive.
|
||
|
.SH HINTS
|
||
|
.B rdjpgcom
|
||
|
does not depend on the IJG JPEG library. Its source code is intended as an
|
||
|
illustration of the minimum amount of code required to parse a JPEG file
|
||
|
header correctly.
|
||
|
.PP
|
||
|
In
|
||
|
.B \-verbose
|
||
|
mode,
|
||
|
.B rdjpgcom
|
||
|
will also attempt to print the contents of any "APP12" markers as text.
|
||
|
Some digital cameras produce APP12 markers containing useful textual
|
||
|
information. If you like, you can modify the source code to print
|
||
|
other APPn marker types as well.
|
||
|
.SH SEE ALSO
|
||
|
.BR cjpeg (1),
|
||
|
.BR djpeg (1),
|
||
|
.BR jpegtran (1),
|
||
|
.BR wrjpgcom (1)
|
||
|
.SH AUTHOR
|
||
|
Independent JPEG Group
|