A saturated pixel in a spot means the brightest part of the reflection was
not measured. The integration used to drop the peak frame's partial (its
peak pixel is unreadable) and keep the flanks, so the combine extrapolated
the event from its tails by the partiality model: on a strongly
diffracting small-molecule crystal the strongest low-order reflections
read 2-3x low and were the largest SHELXL misfits. XDS drops such a
reflection (OVERLOAD); so does rugnux now.
- Integration (CPU + GPU engines): a reflection is `overloaded` when a
signal-disk pixel is saturated, or unreadable on this frame but not in
the run's pixel mask - EIGER/PILATUS write their error value for a
pixel they could not count, which the preprocessor turns into a masked
pixel like a gap's. The engines now receive the PixelMask to tell the
two apart (an earlier attempt that re-classified the marker as
saturation in the preprocessor broke a dataset whose gaps are not in
the file's mask). An overloaded reflection is kept with its box sum,
unfitted, only so its event can be recognised.
- Rotation combine (CPU + GPU): an event with any overloaded partial is
dropped whole; counted in the log and the report
(OBSERVATIONS_REJECTED_OVERLOAD=). The unmerged MTZ export drops it too.
- Everything else that reads reflections leaves an overloaded one out:
AcceptReflection (stills merge, per-image scaling), the post-refinement
gather, the axial-row sums.
- Capture uncertainty: the merge rebuilds each full's variance at the
reflection's mean (counting_variance / ModelSigma) and dropped the
capture term the combine had put into sigma, so a full extrapolated
from part of its rocking curve merged at the weight of a whole one.
Fulls now carry it (Obs::capture) and the rebuilt variance adds
(capture * <I>)^2, host and device.
SHELXL R1 on rugnux's own integration (harness), median fix -> this:
citric acid .0648 -> .0420 (XDS .051; 221 events dropped, EXTI 1.02 -> 0.29),
HEPES .0396 -> .0381 (184), aspirin 20 keV .0387 -> .0385 (6),
aspirin 25 keV .0376 -> .0375 (5); metformin/nidppe/dnba/lalanine/cytidine
no overloads, unchanged. YAG .116 -> .128 (87 dropped; its scale loop does
not settle either way). Proteins and private subset: see the branch report.
Tests: BraggIntegrationEngineCPU_SaturatedPeakIsFlaggedNotDropped (new),
BraggIntegrationEngineGPU_MatchesCPU (overloaded flag compared),
AcceptReflection_ResolutionLimits, [write_reflections], [large].
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
leonarski_fandClaude Opus 5.5
37a8c8e24e