  PRAIA - Package for the Reduction of Astronomical Images Automatically - is a
suite of photometric and astrometric tasks designed to cope with huge amounts
of heterogeneous observations with fast processing, no human intervention,
minimum parametrization and yet maximum possible accuracy and precision. It is
the main tool used to analyse astronomical observations by an international
collaboration involving Brazilian, French and Spanish researchers under the
Lucky Star umbrella for Solar System studies. Here, we focus on the concepts of
differential aperture photometry and digital coronagraphy underneath PRAIA,
used in the reduction of stellar occultations, rotational light curves, mutual
phenomena and natural satellite observations. We highlight novelties developed
by us and never before reported in the literature, which significantly enhance
the precision and automation of photometry and digital coronagraphy, such as:
a) PRAIA's pixelized aperture photometry (PCAP); b) fully automatic object
detection and aperture determination (BOIA); c) better astrometry improving the
aperture and coronagraphy centre, including the new Photogravity Center Method
besides circular and elliptical Gaussian and Lorentzian generalized profiles;
d) coronagraphy of faint objects close to bright ones and vice-versa; e) use of
elliptical rings for the coronagraphy of elongated profiles; f) refined
quartile ring statistics; g) multiprocessing image capabilities for faster
computation speed. We give examples showing the photometry performance, discuss
the advantages of PRAIA over other popular packages, and point out the
uniqueness of its digital coronagraphy in comparison with other coronagraphy
tools. Besides Solar System works, PRAIA can also be used in the differential
photometry and digital coronagraphy of any astrophysical observations. PRAIA
codes are publicly available at: https://ov.ufrj.br/en/PRAIA/.
