#88 CA correction matching according to aperture

[Žilvinas Žaltiena]

Currently lensfun chooses CA correction only by focal length, however CA on some lenses is also dependent on aperture value. I.e.

http://www.lenstip.com/upload2/169422_aber.png

http://www.lenstip.com/upload3/3699_aberracja_11.jpg

http://www.lenstip.com/upload3/4192_aberracja_11.jpg

As of now, it is impossible to correct CA for more than one aperture value, because profile can contain only single TCA entry per any given focal length.

I ask to expand matching of CA corrections so it would take aperture value into account too.

[COMPUTERFREAKED]

I am by far no expert on this but there are 2 different kinds of CA. LCA and TCA.

TCA is independant of aperture and can be more or less corrected in software. Hence no aperture selection is needed for correction.

LCA is aperture dependant but can not be corrected in software as far as i know.

https://photographylife.com/what-is-chromatic-aberration/

[Torsten Bronger]

The dependence of TCA on aperture is very weak and beyond Lensfun's scope. Also note that such an expansion not only means much more complex code (instead of one-dimension interpolation, two-dimensional interpolation would be necessary) but also much more difficulty to create correction data for every lens.

Besides, I second Computerfreaked's concern that LCA may be mixed up with TCA in your images.