Chromatic aberration correction: Lensfun vs Automatic (raw tab)

Software RawTherapee
1

In my use I’ve noted the following about the different types of ca correction

  1. Raw tab auto correction

    1. Changes the colour of the image
    2. Removes CA very well
    3. Works well with highlight reconstruction

  2. Lensfun TCA correction

    1. Depends on quality of profile
    2. Highlight reconstruction can produce false colour
    3. Affects only lateral (transversal) CA without altering the overall colour of the image much

For my use case 1.3 and 2.3 are both highly desirable because there are frequently some over exposed areas and I appreciate the colour rendering of my system and want to maintain those colours. Unfortunately they are currently mutually exclusive.

See gif below showing an animation of a slightly oof tree against sky in the corner of a uwa lens with the various corrections applied

230122-RT_CAfix

As you can see even in the indexed gif the change in sky colour is quite dramatic.

Does anyone have any tricks or solutions to solve the conflict? When handling lots of images it’s easy to miss it when one of the default tools in your workflow create a problem so I’m always looking for robust solutions.

I’d also appreciate info on how the tools work. I’m guessing that the highlight reconstruction fails to take lensfun tca into consideration due to it coming later in the pipeline. Any info on how or why automatic correction works would also be appreciated. I have some lenses with quite uneven tca but automatic seems to solve it despite the magnification of the channels varying across the frame.

2

On my 5.9 version of Rawtherapee, the CA correction on the RAW tab has the option “avoid colour shift” which can be ticked. So just to exclude possible causes: Does the colour shift also occur when you tick that option?