Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

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)



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner