  EUSO-SPB1 was released on April 24th, 2017, from the NASA balloon launch site
in Wanaka (New Zealand) and landed on the South Pacific Ocean on May 7th. The
data collected by the instruments onboard the balloon were analyzed to search
UV pulse signatures of UHECR (Ultra High Energy Cosmic Rays) air showers.
Indirect measurements of UHECRs can be affected by cloud presence during
nighttime, therefore it is crucial to know the meteorological conditions during
the observation period of the detector. During the flight, the onboard
EUSO-SPB1 UCIRC camera (University of Chicago Infra-Red Camera), acquired
images in the field of view of the UV telescope. The available nighttime and
daytime images include information on meteorological conditions of the
atmosphere observed in two infra-red bands. The presence of clouds has been
investigated employing a method developed to provide a dense cloudiness map for
each available infra-red image. The final masks are intended to give pixel
cloudiness information at the IR-camera pixel resolution that is nearly 4-times
higher than the one of the UV-camera. In this work, cloudiness maps are
obtained by using an expert system based on the analysis of different low-level
image features. Furthermore, an image enhancement step was needed to be applied
as a preprocessing step to deal with uncalibrated data.
