  Pesticide application has been heavily used in the cultivation of major
crops, contributing to the increase of crop production over the past decades.
However, their appropriate use and calibration of machines rely upon evaluation
methodologies that can precisely estimate how well the pesticides' spraying
covered the crops. A few strategies have been proposed in former works, yet
their elevated costs and low portability do not permit their wide adoption.
This work introduces and experimentally assesses a novel tool that functions
over a smartphone-based mobile application, named DropLeaf - Spraying Meter.
Tests performed using DropLeaf demonstrated that, notwithstanding its
versatility, it can estimate the pesticide spraying with high precision. Our
methodology is based on image analysis, and the assessment of spraying
deposition measures is performed successfully over real and synthetic
water-sensitive papers. The proposed tool can be extensively used by farmers
and agronomists furnished with regular smartphones, improving the utilization
of pesticides with well-being, ecological, and monetary advantages. DropLeaf
can be easily used for spray drift assessment of different methods, including
emerging UAV (Unmanned Aerial Vehicle) sprayers.
