Ports the sharpest-frame selection from scanpe_experiments/h3_image.py, which
takes it from IF-Edit (arXiv:2511.19435): decoded frames carry different amounts
of residual motion blur, so score by Laplacian variance and keep the crispest
instead of a fixed index.
Pairs with running MiniMax-H3 as an image generator: the VAE's minimum clip is 5
pixel frames (2 latents), decode yields frames of uneven sharpness, and the best
one is not always at the same index.
The node documents a limitation found while testing it, because it is easy to
misuse: Laplacian variance is a BLUR heuristic, not a quality metric -- artifacts
are high-frequency too. On a real H3 decode it picked the frame with the WORST
PSNR of its block (19.72 dB against 23.19 for its neighbour) because that frame
was the most artifacted. It is sound when the candidates are the same content
differing only in blur, which is the IF-Edit setting; it is meaningless for
choosing among frames from different moments.
Also relevant and not obvious: the "last frame of each decoded block is the valid
one" rule (decoded[:, :, -1] in the upstream example) held for the first block
here (34.49 dB against 26.80 for its neighbour) but inverted on the second.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
