LumiGrid can now be tried on your own photo right on the site. Both networks run on the visitor's device; nothing is uploaded.
The browser version of LumiGrid: input on the left, result on the right, per-step timings on the side
Compared pixel by pixel with PyTorch, the largest difference is a single grey level (63.9 dB). On the way I found that ONNX Runtime Web's WebGPU backend miscomputes convolutions with six input channels; the whole story is in the research note.