rdjpgcom(1) [debian man page]
RDJPGCOM(1) General Commands Manual RDJPGCOM(1) NAME
rdjpgcom - display text comments from a JPEG file SYNOPSIS
rdjpgcom [ -raw ] [ -verbose ] [ filename ] DESCRIPTION
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. 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. OPTIONS
-raw Normally rdjpgcom escapes non-printable characters in comments, for security reasons. This option avoids that. -verbose Causes rdjpgcom to also display the JPEG image dimensions. Switch names may be abbreviated, and are not case sensitive. HINTS
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. In -verbose mode, 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. SEE ALSO
cjpeg(1), djpeg(1), jpegtran(1), wrjpgcom(1) AUTHOR
Independent JPEG Group 02 April 2009 RDJPGCOM(1)
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rdjpgcom(1) User Commands rdjpgcom(1) NAME
rdjpgcom - display text comments from a JPEG file SYNOPSIS
rdjpgcom [-verbose] [filename] DESCRIPTION
rdjpgcom reads the named JPEG or JFIF file, or the standard input if no file is named, and displays any text comments found in the file on the standard output. The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file. Although the standard does not actually define the intended function of COM blocks, they are widely used to hold user-supplied text strings. This enables you to add annotations, titles, index terms, and so on to your JPEG files, and later retrieve the COM blocks 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 many COM blocks in one JPEG file. OPTIONS
The following options are supported: -verbose Causes rdjpgcom to also display the JPEG image dimensions. OPERANDS
The following operands are supported: filename The name of the JPEG file that contains text comments. EXTENDED DESCRIPTION
rdjpgcom does not depend on the IJG JPEG library. The rdjpgcom source code is intended to illustrate the minimum amount of code required to parse a JPEG file header correctly. In -verbose mode, rdjpgcom also attempts to display the contents of any "APP12" markers as text. Some digital cameras produce APP12 markers that contain useful textual information. You can also modify the source code to display other APPn marker types. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWjpg | +-----------------------------+-----------------------------+ |Interface stability |External | +-----------------------------+-----------------------------+ SEE ALSO
cjpeg(1), djpeg(1), jpegtran(1), wrjpgcom(1) NOTES
This man page was originally written by the Independent JPEG Group. Updated by Breda McColgan, Sun Microsystems Inc., 2004. SunOS 5.10 26 Mar 2004 rdjpgcom(1)