Ever noticed how an aggressive resizer such as B-Spline 2-pass can make compressed footage look harsher, bringing out chroma bleeding, messy colour transitions and other distracting artefacts like banding or noise ?
I've made for this a pre-resize HLSL shader for PotPlayer designed to help address these problems before scaling takes place by gently cleaning up unstable chroma transitions and isolated colour outliers in the decoded image while trying to preserve genuine colour edges and fine detail.

What does it actually improve? The most noticeable result has been a subtle but surprisingly effective sense of greater overall clarity, the image looks cleaner and more coherent without the obvious smoothing or loss of fine detail associated with stronger filtering.

The other important benefit is how the image holds up through the rest of the rendering pipeline:
With heavily compressed sources and aggressive resizing, irregular colour transitions can become much more noticeable after enlargement, preparing the image beforehand can help keep chroma bleeding and distracting artefacts under control rather than allowing the resizer to make them more apparent, this also helped avoid unwanted banding and similar artefacts becoming noticeably visible.

This shader works on decoded RGB, adapting its spatial chroma correction to local image structure, it's not an upscaler and cannot recover detail already lost to compression nor does it guarantee that every type of banding or compression artefact can be removed.

Its purpose is to give the resizer/upscaler a cleaner starting point without indiscriminately smoothing the picture.

Download: https://github.com/aston89/ChromaWeave-Adaptive-Repair-shader-for-PotPlayer

The repository README includes installation instructions, technical details, diagnostic modes and other useful things to know.

I'd be interested in hearing how it performs on other heavily compressed SD sources, particularly when paired with B-Spline 2-pass or other high-quality resizers. Feedback and comparisons are very welcome.