The protection against a per-frame scale collapsing toward zero lived inside
ComputeSmoothGWindow, so it only existed when smooth-G did: --smooth-g=0, a
dataset whose oscillation width is unknown, and any caller that never sets a
smoothing range - the viewer among them - merged with no guard at all. A
collapsed G multiplies that frame's intensities by 1/G and its sigmas by the
same factor, so nothing downstream can see it; the merge's n-sigma cut scales
with the number that is wrong.
Pull it out into ReplaceCollapsedScales, called unconditionally right after the
partial scaling loop, and let the smooth-G window assume what it now guarantees
instead of computing its own median and floor.
The fulls guard built its median from every frame including those never fitted -
those sit at the combine's corr = 1, so a run with many unfitted frames dragged
the median toward 1 and the floor with it. It also reported the absolute
amplification where the message says "below the run median".
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 5
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