Help with widescreen letterbox striping artifacts?

[Intermodiate]

Novice encoder here with a first time post. I am consistently seeing some artifacts in newer DVD releases that have me stumped. I'm loathe to post about it because it's so consistent that I'm sure it must be a well known thing - except I just can't seem to Google the right way to get to the thread or article about it. I'm happy to follow any links you might have if you don't feel like retyping some tired old answer.

In all the more modern anamorphic widescreen DVDs I've ripped with MakeMKV, there is some kind of microbanding or something at the top and bottom edges of the video content right next to the letterbox border. I've attached a snap from VLC for Bladerunner 2049 that shows it. In the upper left hand corner is a red box highlighting the artifacts. I've also included a zoomed-in pic. As you can see, it's like some 1px luma stripes, and they extend into the letterbox area as well as the content, and gradually fade. In some films, they're very distracting because they make bright colors really stand out like a neon stripe.

This screenshot is from the MPEG-2 rip right out of MakeMKV. It's present in every modern release I have: 28 Years Later, Alien Romulus, Blade Runner 2049, Edge of Tomorrow, Quantum of Solace. They're even in a recent release of Alien, and a 2006 release of The Good, The Bad, and the Ugly - and those are ancient. I haven't noticed it in older 16:9 or 4:3 releases.

I do not have a regular DVD player that I can hook up to a TV and check to be sure.

My question: What is this and how do I fix it? I'm hoping it's just some setting or filter I can turn on. I don't know that I'm ready to jump into amateur remastering.

Thanks!

[poisondeathray]

It's resampling artifact caused by a negative lobe resampler (someone downscaled not ideally)

One way to address it is avisynth - crop letterbox borders, filter top and bottom frame edges with bbmod, then add back the borders

bbmod function can be found in balanceborders
https://github.com/realfinder/AVS-Stuff/blob/master/avs%202.5%20and%20up/BalanceBorders.avsi

The script would look like this

#source filter
#make sure it's progressive or IVTCed if telecined

Crop(0,58,0,-62)
bbmod(ctop=4, cbottom=4)
AddBorders(0,58,0,62)

[Intermodiate]

Thanks for the quick reply. That looks really promising! I will report back once I figure out how to use AviSynth.