Reflexif is a pure Python Exif library that will be developed here from existing code of my own that is lying around in my private repositories. Reflexif is not ready to be used yet. This README will be updated as the development progresses.
The planned core features cover:
- a low-level API to read and write (raw) Exif/TIFF data structures
- a high-level API to read and write Exif tags as key-value pairs that allows a high degree of control over the writing process
- a transparent (and controllable) mapping between raw values and normalized / pretty print values
- a plugin architecture to implement makernotes, custom value mappings and other hairy bits separately from the rest of the project
Reflexif will take special emphasis on providing a sensible low level API that exposes the actual TIFF/IFD data structures, which is important if you want to control the process of how modified Exif tags are written to a file (which again is cumbersome and possibly hazardous).
The most important use case I have myself is a minimally invasive modification of Exif tags in my orignal digital images (e.g. orientation, timestamps, geotags), without keeping duplicates and without having the entire Exif data and/or Image file rewritten.
This github repository acts as the official project homepage. A separate sphinx documentation will be hosted somewhere else at some point in the future. For the time being, please consult the source code.
Reflexif has not been uploaded to PyPI yet since there have not been any releases. However, you can install Reflexif directly from this git repository via:
pip install git+git://github.com/chschmitt/reflexif.git
Beware: There is not much to be used yet. Consult the top section for information on the development progress.
TL;DR I think that a permissive-licensed Exif library that provides low-level access to the Exif data structeres and that is entirely written in Python might address an acutal gap in the Python ecosystem.
As with every new software project, you may of course challenge whether there is an actual need for it. While thers is IMHO no definitive answer to that, there are a few reaons for me to develop Reflexif.
The usual functionality that is provided by Exif libraries to the using application is to read (and sometimes write) Exif tags as key-value pairs. This is a useful abstraction for high-level APIs to access Exif data. Logically, the complexity of the data structures and especially the manipulation/writing process is then usually hidden. If it is important to you, how your image files are modified, this may leave you with too little transparency or even control.
The arguably most complete Exif implementation that can be used with Python is exiv2. It is available via gexiv2 (a GObject wrapper) and pygobject (a generic GObject binding for Python).
While exiv2 is a great piece of software, I do not like the detours you have to take to use it with Python. If you want to know what I mean, please try compiling gexiv2 and its dependencies on a machine that has an outdated version of glib.
I am a big fan of open source and the goals of the GPL. However, I do not know where the projects I am dealing with will take me eventually. So I chose not to rely too heavy on GPL'ed libraries (such as gexiv2).
In addition, permissive licenses are the normal case in the Python ecosystem in terms of numbers (see PyPI) and (IMHO) user expectations, since most of the large and prominent Python projects (such as NumPy or Django) use permissive licenses.
Reflexif will be developed and tested against CPython 3.3+, with focus on the current Python realease.
I will also try to keep everything working with Python 2.7, but I will not optimize
for it. For example, I won't make detours to use dict.iteritems() and its
companions to save memory.
Testing against PyPy, IronPython and Jython has no priority, but I might have a look at it at some point.
Reflexif does currently not depend on other projects othen than setuptools,
which is needed for installation anyway. To be precise, the plugin architecture
will rely on the entry point API provided by pkg_resources
(included in setuptools).
There is no roadmap with dates and milestones as I am working on Reflexif on my own accord and when I have the time to do so.
Reflexif will use semantic versioning. Prior to release 1.0.0, breaking changes may occur at any increment. Everything will take place in the master branch.
I am open to receive pull requests. If you plan larger contributions or changes to Reflexif, please ope and issue first in order to make sure that everything fits in nicely. By submitting a pull request, you accept to publish your contributions under the same license. You will be added to the AUTHORS file.
Note: Since I am currently the only author and copyright holder, there is only me in the LICENSE file and there is no AUTHORS file to keep things simple for now. This will be changed when the first contribution will be merged into the repo.
This project published under the 3-clause BSD license. See the LICENSE file.