From b7a7008b8236a2035241935d1276e7113d1fc82c Mon Sep 17 00:00:00 2001 From: Thomas White Date: Thu, 27 Nov 2014 15:12:31 +0100 Subject: Fix pre-merging Poisson error calculation for low photon counts --- libcrystfel/src/integration.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'libcrystfel/src/integration.c') diff --git a/libcrystfel/src/integration.c b/libcrystfel/src/integration.c index 4edc0c56..edc6e7eb 100644 --- a/libcrystfel/src/integration.c +++ b/libcrystfel/src/integration.c @@ -1633,9 +1633,10 @@ static void integrate_rings_once(Reflection *refl, struct image *image, sig2_poisson = aduph * intensity; /* If intensity is within one photon of nothing, set the Poisson - * error to be one photon */ + * error to be one photon. Pretend I = 1 photon = 1*aduph, + * then sig2_posson = aduph*intensity = aduph^2. */ if ( fabs(intensity / aduph) < 1.0 ) { - sig2_poisson = aduph; + sig2_poisson = aduph * aduph; } /* If intensity is negative by more than one photon, assume that -- cgit v1.2.3