Overprocessing terms.

In photography and digital image processing, the unsightly bright or dark bands that appear along high-contrast boundaries after over-processing are most commonly called halos. 

Technically, these effects are a form of ringing artifacts. Depending on the specific tool used and the nature of the artifact, they are also referred to by several other names: 

Common Terms for Edge Artifacts

• Halos: The standard creative term for the glowing white or dark outlines that appear when contrast, clarity, or sharpening sliders are pushed too far.

• Ringing Artifacts: A technical term for "ghost" signals or ripples that oscillate near sharp transitions in an image, often caused by aggressive sharpening or compression.

• Overshoot and Undershoot: In signal processing, the bright band is an "overshoot" (the signal went too high), and the dark band is an "undershoot".

• Edge Fringing: Often used when the edges have a distinct color (like purple or cyan), though this is more specifically known as chromatic aberration.

• Gibbs Phenomenon: The mathematical term for the ringing that occurs when high-frequency data is lost during processing or reconstruction. 

Primary Causes of Halos

1. Over-sharpening: Sharpening works by increasing the contrast exactly at the edge; if overdone, the light side becomes too white and the dark side too black.

2. Excessive Clarity/Texture: These sliders increase "local contrast." Because they affect a broader area than standard sharpening, the resulting halos look like a thick, unnatural glow.

3. Aggressive HDR Processing: Merging multiple exposures can create bright halos where dark objects (like mountains) meet a light sky.

4. Heavy Shadow/Highlight Recovery: Drastically darkening a sky while brightening the foreground can leave a "seam" of unadjusted pixels at the horizon line. 

   
   

So there you have it. There’s proper names for all those unnatural effects you see in some not quite perfect post production images.

It doesn’t matter how much you try to convince an audience that your halos are deliberate and are part of a ‘look’ I doubt you’ll convince many. Certainly not a judge.