Although "Reference Image Blend %" has simple technical interpretation, it is often inconvenient, because it sould be readjusted every time when
frame acquision rate is changed. If pre-alarm and alarm acquision rates differ, it creates another problem. If for example, alarm rate is higer, then this may lead to alarm oscillations - low pre-alarm rate predispose to initiation of alarms, high alarm rate tends to turn alarms off due to faster signal decay (blending goes faster at higher frame rates).
I suggest using blending time Tblend instead of Reference Image Blend %:
Tblend = 100*dt/RIB%,
where:
dt = time period between frames
RIB% = Reference Image Blend %
Tblend is time that it takes to effectively replace previously accumulated reference image (i.e. its relative contribution will be = exp(-1) ~ 27%). Given Tblend it is easy to compute RIB% factor (ideally, this should be done for every frame):
RIB% = 100*dt/Tblend