The disclosure notably relates to methods, devices, programs and other data structures related to machine-learning an artificial neural network function configured for analyzing microscope images of microalgae culture samples with respect to one or more biological attributes. The one or more biological attributes comprise a category among a predetermined set of categories which includes a plurality of microalgae species and/or genera and at least one non-algae micro-organism category. The one or more biological attributes further comprise a physiological state among a predetermined set of microalgae physiological states. The artificial neural network function forms an improved solution for analyzing microalgae culture sample.