JSol'Ex : solar image processing written in Java By Cédric Champeau

The Sol'Ex (aka "Solar Explorer") is a home made instrument invented by Christian Buil, which enables observations of the sun in different wavelengths. It is a kind of so-called "spectroheliograph", an instrument which was invented back in 1890. With modern technologies like CMOS cameras, we can now build cheap devices which makes observing the sun accessible to everyone. What is interesting, however, is that such a device doesn't directly produce an image: software processing is mandatory, because we need to reconstruct an image from a video which only contains images of a portion of the light spectrum. With Sol'Ex, this processing has traditionally be done with INTI, a program written in Python co-authored by Christian Buil. As an amateur astronomer, I've been used to using software for astronomy image processing, but as a developer, I hadn't implemented anything myself yet. Therefore I challenged myself and started a project in order to write my own processing software, called JSol'Ex, written in Java. This project was started as an experiment, so that I understand the "science" behind the image reconstruction, and see if I was still capable, after 20+ years of programming, to implement algorithms based on research papers. In this session, I will explain what I have learnt: the principles of capturing images with the Sol'Ex instrument, how images are reconstructed, but also the various features I have added to JSol'Ex which make it now quite unique in its domain. CÉDRIC CHAMPEAU Cédric Champeau works for Oracle Labs, in the GraalVM team and in particular on the Micronaut framework. He is specialized in developer productivity and maintains among others the official GraalVM and Micronaut plugins for Gradle and Maven. He has worked for Gradle Inc. for several years on dependency management and other developer productivity issues. A former contributor to the Groovy language, he implemented its static compiler. Outside of computing, Cédric is an astronomy enthusiast.