This site is all about the Lensfun library. What is it, you may ask?

Digital photographs are not ideal. Of course, the better is your camera, the better the results will be, but in any case if you look carefully at shots taken even by the most expensive cameras equipped with the most expensive lenses you will see various artifacts. It is very hard to make ideal cameras, because there are a lot of factors that affect the final image quality, and at some point camera and lens designers have to trade one factor for another to achieve the optimal image quality, within the given design restrictions and budget.

But we all want ideal shots, don’t we? :) So that’s what’s Lensfun is all about – rectifying the defects introduced by your photographic equipment.

Latest news

2019-02-16 The past, the current state and the future

The Lensfun project was started by Andrew Zabolotny in 2007 to lay the foundation of a free and open source database for the correction of photographic lens errors. After Lensfun did not receive any more fixes and database updates, I more or less took over the maintenance from Andrew in 2012. Afterwards, my main focus was to continuously integrate the submitted profiles and database changes and to regularly release new versions to make these changes available for the application users.

From 2012 till today a lot of changes and improvements came to the Lensfun project. Torsten Bronger established the calibration webservice and GitHub repo where today most of the calibration work is done by a couple of people. He also dived deep into the maths behind the corrections and fixed many errors and inaccuracies. Many other people contributed fixes, lens profiles and tutorials with instructions and scripts to facilitate the calibration process.

If we look at the number of lens profiles for each release, we can see that there is an increasing growth and the Git master database now nearly counts 1000 lens profiles.

Version #
0.2.6 350
0.2.7 374
0.2.8 441
0.3.0 580
0.3.1 667
0.3.2 714
Master 978

More and more image editors and even some commercial applications today use Lensfun and its database for their processing. That’s a great achievement and underlines the importance of the project.

In 2016 I started to refactor most of the library internals as it turned out that its structure cannot be extended, e.g. with the perspective correction now available in the alpha release, and was really difficult to maintain. A lot of code has been modernized and cleaned up to make Lensfun ready for the future. But unfortunately, the time I can spent in coding for the Lensfun project since then has decreased a lot and today the project is more or less stalled.

However, there is still a lot of work to be done. Just to name a few things that seem to be important to me:

1) Create a new stable release

2) Allow database lens entries that contain calibration data from various crop factors. Lensfun then just picks the closest one for each requested modification.

3) Move the complete project to GitHub and modernize the project infrastructure and build system. Use Travis CI and Appveyor for testing.

4) Develop a strategy how to decouple the database from the library source code to allow a faster release of new profiles to the user base. There is already the lensfun-updata-data script, but this only works reliably on Linux and not on OSX and Windows until now.

Currently, I do not have time to maintain the Lensfun project in way that is satisfactory for myself, for the community and for the users. This project really needs someone who takes a look at the bigger picture and has the vision and motivation to keep the project alive and in a good condition.

Therefore, I would like to ask the community to take over the Lensfun project management and maintenance in the next months. I will still be around and contribute from time to time. But to be realistic, none of the above listed changes will happen if no one else kicks in and does the job. Ideally, Lensfun is taken under the hood of a bigger project with experienced developers like e.g. Darktable or Rawtherapee that already makes use of Lensfun.

Let me know if you want to get involved!

2018-06-29 Alpha release 0.3.95

This is an alpha release and snapshot of the current development. During the last years, major parts of lensfun’s internals have been restructured and refactored to make Lensfun ready for the future. We believe many things have been improved and we tackled some issues that have been discussed for a long time. However, nothing is perfect. We highly encourage all users of Lensfun to try this alpha version, provide feedback and help us to improve whatever is necessary and get a stable release, soon. An up-to-date list of open issues and discussion points can be found in the Wiki at Sourceforge.

Apart from the breaking changes listed at the end, all changes should be backwards compatible but many functions and variables have been marked as deprecated to encourage the use of the new improved API.

General changes

  • Overall we received 208 new profiles and 64 profile updates. Thanks to all the contributors!
  • Added support for the Adobe Camera Model (ACM) for distortion, TCA, and vignetting. It also covers fisheye models. Lensfun includes a script which can convert Adobe lens profiles into Lensfun.
  • New perspective correction feature
  • The <distortion> tag now may have a real-focal attribute with the actual focal length at this particular nominal focal length. It replaces the <real-focal-length> tag.
  • Due to the previous changes, the database format is now at version 2.
  • Binary version number has been incremented to version 2.
  • Torsten Bronger’s calibration tutorial, his webserver code for receiving calibration images, and his calibration script are now part of Lensfun’s source code.
  • Lensfun is now internally prepared to support multiple calibrations per lens, e.g. for different crop factors.
  • Internally make use of C++ STL containers instead of glib arrays or proprietary container formats.
  • Use various C++11 features, hence compilation now requires a compiler supporting C++11.
  • Static lfXX::Create() and lfXX:Destroy() methods of various Lensfun classe are now marked as deprecated. C++ new/delete syntax should be used instead.
  • Remove dependency to POSIX regex.h and TRE regex on windows, instead use std::regex on all platforms.
  • CMAKE: glib > 2.26 is now only required when tests are being build.
  • CMAKE: various fixes (paths, OS compatibility).

A detailed list of changes can be found in in the complete Changelog for 0.3.95.

Breaking changes

  • C interface: all lf_lens_interpolate_...() functions now require an additional crop parameter.