Hi Andrew (and others), I'm very happy that there is something happening here, since it is unlikely that I will have the time to do much work in this area.
Here are some comments (I haven't had a very close look at the interface yet). The lf_corrector_apply does not allow different transformations for the color channels (which is required for TCA correction). TCA behaviour of most lenses is close to linear, but some specific ones (especially some fisheye lenses) exhibit a non-linear relationship. I provided Michel Thoby with some software to measure the TCA, and he has put a lot of work into testing different lenses and TCA correction tools. A comparison of tools is available at: http://michel.thoby.free.fr/Compare_Fisheyes/Correction_TCA/Illusion_and_reality_TCA.html To me it seems that photoshop is doing more than just a mere scaling of red and blue channels. Also, TCA should not vary with different aperture settings. It will probably vary a little bit with the subject distance. There is a nice paper (which I don't have handy right now :-( ) on how the k1 distortion coefficient can be interpolated across different focal lengths, by fitting a exponential function to the measured (distortion,focal length) values. This is much better than linear interpolation. I have been doing some work on the stability and estimation procedure for the radial distortion part, but I need some more work to reach final conclusions. However, the traditional k1, k2 model seems to work quite well for most rectilinear lenses. I have written some example xml files and a tool to convert the PTLens database that might be helpful for inspiration, they are available at: http://hugin.svn.sourceforge.net/viewvc/hugin/lensdb/trunk/ ciao Pablo Andrew Zabolotny wrote: > Here I am again :) > > I thought I'd post a progress report on this task, such that interested > persons would know it's not dead :-) > > I have finished the first implementation of database management, it > supports database loading (from multiple file/locations automatically, > like I suggested before), saving to XML, supports several types > of database queries (including fuzzy lens search). > > The doxygen docs for the library interface can be found here: > > http://cs.ozerki.net/zap/lensfun/doc/ > > Here's a simple example applications that loads the database, does a > few queries and saves the results to a new xml file: > > http://cs.ozerki.net/zap/lensfun/tfun/ > > You can see a sample of database format in the file saved by the > example application. > > Comments are still welcome, as the interface has not been frozen > yet ;-) (hey, it's just a week since I started ;-). > > The image correction logic is totally missing at this time, just a > draft of the interface is present. I'll proceed with this today. > > As soon as project stabilizes a bit, I'm going to upload it to > sourceforge. > > > > ------------------------------------------------------------------------ > > _______________________________________________ > CREATE mailing list > [email protected] > http://lists.freedesktop.org/mailman/listinfo/create _______________________________________________ CREATE mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/create
