Polarimetric observables for the enhanced visualization of plant diseases

This paper highlights the potential of using polarimetric methods for the inspection of plant diseased tissues. We show how depolarizing observables are a suitable tool for the accurate discrimination between healthy and diseased tissues due to the pathogen infection of plant samples. The analysis is conducted on a set of different plant specimens showing various disease symptoms and infection stages. By means of a complete image Mueller polarimeter, we measure the experimental Mueller matrices of the samples, from which we calculate a set of metrics analyzing the depolarization content of the inspected leaves. From calculated metrics, we demonstrate, in a qualitative and quantitative way, how depolarizing information of vegetal tissues leads to the enhancement of image contrast between healthy and diseased tissues, as well as to the revelation of wounded regions which cannot be detected by means of regular visual inspections. Moreover, we also propose a pseudo-colored image method, based on the depolarizing metrics, capable to further enhance the visual image contrast between healthy and diseased regions in plants. The ability of proposed methods to characterize plant diseases (even at early stages of infection) may be of interest for preventing yield losses due to different plant pathogens.We acknowledge the financial support of Spanish MINECO (RTI2018-097107-B-C31, and Fondos FEDER); Catalan Government (2017-SGR-001500). J. L. was supported by the CERCA Program, Generalitat de Catalunya.Abstract Introduction Results Polarimetric analysis of chlorosis and necrosis Pseudo-colored approach Discussion Methods Sample description Mueller–Stokes formalism Polarimetric observables Complete image Mueller polarimeter Data availability References Acknowledgements Author information Ethics declarations Additional information Supplementary Information Rights and permissions About this article Comment