So this is where the "lummox pls add feature" comes in. It'd be amazing if filters supported the ability to define arbitrary HLSL shaders instead of the current pre-defined shaders. While this would have a couple of limitations due to BYOND using DirectX9 (DX9 lacks compute shader support, making specific edge cases pretty hard to actually pull off in a way that doesn't affect performance), this would still offer a level of flexibility that filters currently lack.
Ideally, passing an HLSL shader to a filter would be fairly simple, and would ideally look something like this:
filter(file = 'shaders/genericlibrary.hlsl', type = "generictechniquenamegoeshere", arbitraryparam = 0.3)
I'm not sure how hard it would be to implement, but it would be a fantastic way to put the graphical fidelity of BYOND projects into the hands of the developers behind them, while also letting the current library of existing shaders continue to exist for those that don't want to learn HLSL.