rdjpgcom - display text comments from a JPEG file
rdjpgcom [-verbose] [filename]
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.
The following options are supported:
-verbose Causes rdjpgcom to also display the JPEG image dimensions.
The following operands are supported:
filename The name of the JPEG file that contains text comments.
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.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE ATTRIBUTE VALUE Availability SUNWjpg Interface stability Volatile
cjpeg(1), djpeg(1), jpegtran(1), wrjpgcom(1)
This man page was originally written by the Independent JPEG Group. Updated by Breda McColgan, Sun Microsystems Inc., 2004.
|SunOS 5.11||rdjpgcom (1)||26 Mar 2004|