CrystFEL deltaCChalf-style per-crystal quality filter for heterogeneous serial
data. Each image is assigned to one CC1/2 half, so removing it perturbs only that
half's per-reflection means; deltaCChalf_i = CC1/2(all) - CC1/2(without image i).
A negative value means dropping the image RAISES CC1/2 (it disagrees with the
consensus). Images whose deltaCChalf is a low-side statistical outlier
(< mean - N*stddev) are skipped when merging. Reference-free.
Two passes over the retained integration outcomes; per-image contributions are
re-derived rather than stored, so memory stays O(unique reflections + images) for
full 200k-frame runs. New CLI flag --reject-delta-cchalf <N> (default: off).
Validation (jet FFBIDX +C+S, sigma4): removing 17/4000 (3 sigma) raises CC1/2
95.1->96.1%, CCref 54.9->55.2; 2 sigma -> 96.1/55.3. Dataset-appropriate: it HELPS
heterogeneous serial data (some crystals genuinely bad) but slightly trims a
homogeneous single rotation crystal (c2 94.6->93.8 - no bad crystals, the relative
cut still removes the tail), so it is opt-in. R-free is the real test (user's full
200k). Note: the reported overall N_obs still counts all observations; the exported
merge (and CC1/2) correctly exclude the rejected images.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
leonarski_fandClaude Opus 4.8
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