lens correction and gradient [reported]

Software darktable
1

I developed some pictures that were taken with a LX100II, fixed lens, variable focal length lens camera.
Especially on the wide end the lens shows a bit of distortion which is nicely taken care of by the lens correction module.
Next step I wanted to darken the sky with gradient mask on the exposure module. What I realized is, that the gradient mask was no longer straight but warped and that setting the angular adjustment of the gradient becomes very difficult as it resets to certain positions.

Resetting the lens correction solves that issue but than I have a straight gradient over a curved horizon line.

The warp of the gradient seems to be reciprocal to the distortion correction of the lens correction module.

Maybe someone can test it as well so I can file a bug report? Or is it wanted system behavior?

  1. Load a picture with discarded history (used lens should distort visibly and correction module should be available)
  2. Activate Lens Correction module
  3. Activate Exposure module. Select a gradient. Is it already warped? Turn the gradient. Does it jump back a little after you release it?

Edit
oh yes, dt 3.0.1, Ubuntu 18.04 and lensfun-update-data

2

There is already a similar issue raised on github, though I’d assumed it was introduced by a change that’s not in 3.01. You could add some detail to that:

1 Like
3

Thanks for the heads up. I did a search but that one I did not find.
It exactly describes my issue so it is a known problem. Thank you for pointing me in the right direction.

1 Like
4

added my info to github

5

Thanks for adding this.

I tested a slew of different camera (RAW) types on dt development 3.1.0, but this was before 3.0.1 was released.