  In photo-sensor cameras of Cherenkov telescopes the light images from
particle showers always contain the background noise induced by photons of the
night sky. An image cleaning procedure is needed to reduce the contribution of
those noise photons in further analysis stages. The conventional topological
next neighbor method lacks reconstruction efficiency for low light content
images and image peripheries with low signal levels. We present here a simple
optimization of the traditional next-neighbor image cleaning method that
exploits the limited time duration of shower flashes and short time-difference
between neighboring image pixels. This method reduces greatly the noise
contribution by applying dynamical cuts in the parameter space formed by signal
amplitude and time-difference between neighboring pixels
