  We present a robust imaging method based on time-correspondence imaging and
normalized ghost imaging (GI) that sets two thresholds to select the reference
frame exposures for image reconstruction. This double-threshold
time-correspondence imaging protocol always gives better quality and
signal-to-noise ratio than previous GI schemes, and is insensitive to
surrounding noise. Moreover, only simple add and minus operations are required
while less data storage space and computing time are consumed, thus faster
imaging speeds are attainable. The protocol offers a general approach
applicable to all GI techniques, and marks a further step forward towards
real-time practical applications of correlation imaging.
