How is it called and how to remove it?

[tormento]

https://i.ibb.co/pJyvwh9/S09-D1-168-174-00.png (https://ibb.co/pJyvwh9)

https://i.ibb.co/XYP8w75/S09-D1-168-174-01.png (https://ibb.co/XYP8w75)

I have properly (I hope ;) ) resized Bleach BD from 1920×1080 to 960×540 but it seems that the "halo" close to the black border isn't a upscale artifact, as it stays where it was.

How is it called and how to remove it properly without neither cropping nor losing image quality.

Here (https://pixeldrain.com/u/JxV3SNax) a short clip.

[Selur]

If cropping the black bars and adding them back after filtering is an option, you could Crop,BalanceBorders,AddBorders (https://imgsli.com/Mjg2MzE2).

Cu Selur

[tormento]

If cropping the black bars and adding them back after filtering is an option, you could
Look at the cloud.

Perhaps I am a bit too picky but I can still see the halo.

[Selur]

Increasing the top values (8 or 10) in BalanceBorders should help, but this will only work around edges. if you use too high values it will cause visible smearing,...

Cu Selur

[tormento]

Increasing the top values (8 or 10) in BalanceBorders should help, but this will only work around edges. if you use too high values it will cause visible smearing
I've found many, many versions and mods of BalanceBorders.

Can you link me the one you use?

[Selur]

I used Vapoursynth's BalanceBordersMod (https://github.com/Selur/VapoursynthScriptsInHybrid/blob/80a7196e2eef0bd3bacf5e706d924d0d9bbd948d/havsfunc.py#L4495) which should be the same as https://github.com/Asd-g/AviSynthPlus-Scripts/blob/master/bborders.avsi

[Arx1meD]

Try Edgefixer (https://github.com/sekrit-twc/EdgeFixer)

For example, fix black (or semi-black) fields:
ContinuityFixer(left=1, top=0, right=2, bottom=0, radius=2)
For example, fix the brightness of a large field:
ref = last.Blur(1.58).Blur(1.58).Blur(1.58)
ReferenceFixer(ref, left=6, top=6, right=8, bottom=6, radius=5)