what is the cause of halo around dark objects (non-HDR)

Question

This problem occurs often with scenes that have trees with the sky behind. I tend to raise the shadows and reduce the higligts (in RAW) to get a more pleasing image, I believe this is a normal thing to do.

Here is a [extreme] demo, original shot:

after raising the shadows (I raised more than usual to make the problem show more):

As you can see, dark has bright halo and bright has dark halo and I noticed that the darker the image the more apparent the effect. Here are my questions:

1. Is this a hardware or a software post processing artefact?

2. if it's hardware then do I have a faulty camera or is this normal?

3. is this the same problem that occurs with HDR shots?

and of course, can it be fixed?

The image was taken with a Sony a6300, 10-18mm lens

EDIT:

1. software used: tried both Luminar 2018 and Darktable

2. the attached images are just screenshots directly form the editing software

Answer 1

It is a processing/software artifact and the same as what is encountered when tone mapping HDR images... that's basically what you are doing; re-mapping the tones, only w/in a single image.

Also check other contrast type settings; sharpening, clarity, etc. Those types of settings try to preserve/increase the perception of details by adding localized contrast; i.e. light next to dark/dark next to light.

Answer 2

Confirming @Steven Kersting's answer, the problem is a software issue caused by some internal tone mapping/local contrast, the "shadows" slider shouldn't normally cause the hallo but in this case it is.

I managed to fix the halo problem using RawTherapee, by sliding the shadows slider I got the results I was expecting (without the halo). This indicates different implementation of the feature, which in my opinion is more accurate: