readme.txt

JHEAD is a simple command line tool for displaying and some manipulation
of EXIF header data embedded in Jpeg images from digital cameras.

For command line options, please see usage.html

There is also a suite of regression tests in the "tests" directory.
After compiling, from the tests directory run "runtests"
To check the results, do "diff expected-txt results-txt"


Some notes:

    When I first wrote Jhead back in 1999, there wasn't much software around
    for looking inside Exif headers, so I wrote jhead for that task.  Since
    then, a lot of much more sophisticated programs for looking inside Exif
    headers have been written, many with GUIs, and features that Jhead lacks.

    Seeing that Jhead does everything I need it to do, My goal is not to have
    every feature imaginable.  Rather, I want Jhead to be a small, simple,
    easy to understand program.  My goal is that if you need to understand
    Exif internals, or add Exif capability to your program, Jhead is the
    place to cut and paste code from.

    If jhead doesn't have a feature you want, look for "exiftool".  Exiftool
    has any feature you could imagine, but it's also 100x bigger and much
    slower.

    If you find that it dies on a certain jpeg file, send it to me, and I
    will look at it.


Compiling:

    Windows:

    Make sure visual C is on your path (I use version 6 from 1998,
    but it shouldn't matter much).
    Run the batch file make.bat

    Linux & Unices:

    type 'make'.

Portability:

    Although I have never done so myself, people tell me it compiles
    under platforms as diverse as such as Mac OS-X, or NetBSD on Mac68k.
    Jhead doesn't care about the endian-ness of your CPU, and should not
    have problems with processors that do not handle unaligned data,
    such as ARM.

    Jhead has also made its way into various Linux distributions and ports
    trees, so you might already have it on your system without knowing.

License:

    Jhead is public domain software - that is, you can do whatever you want
    with it, and include it software that is licensed under the GNU or the
    BSD license, or whatever other license you chose, including proprietary
    closed source licenses.  Although not part of the license, I do expect
    common courtesy, please.

    If you do integrate the code into some software of yours, I'd appreciate
    knowing about it though.

Matthias Wandel