Interesting idea - I haven't explored wavelet-based approaches but the intuition makes sense: decompose into frequency bands, keep the low-frequency trend, and selectively preserve high-frequency peaks that exceed some threshold.

My concern would be computational cost for real-time/streaming use cases. LTTB is O(n) and pretty cache-friendly. Wavelet transforms are more expensive, though maybe a GPU compute shader could make it viable.

The other question is whether it's "visually correct" for charting specifically. LTTB optimizes for preserving the visual shape of the line at a given resolution. Wavelet decomposition optimizes for signal reconstruction - not quite the same goal.

That said, I'd be curious to experiment. Do you have any papers or implementations in mind? Would make for an interesting alternative sampling mode.