sylpheed-port found that my control's premise misreads their figure. The 0.06 %
counts pixels surviving -threshold 25%, differing by more than ~64 levels -- a
gross-displacement detector, blind to sub-pixel offsets and antialiasing, which are
exactly what a per-level LUT also cannot close. It says no gross displacement, not
geometry is right, and I read one as the other.
Their direct measurement, attributed and not reproduced here: after the LUT the
menu's residual is 6.94 on edge pixels against 2.20 on flat, with a known negative
leaving 0.00. So the menu carries spatial error and is not a geometry-free control.
The 32/68 result does not rest on it -- 'whatever a fitted per-level LUT cannot
close is not a per-level effect' is the method's own basis and is self-standing.
What the control shows is narrower than claimed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
93653dcb74