“…The first approaches involved image processing methods based on color and texture descriptors combined with morphology filtering (Berge et al, 2011;Chadha et al, 2020). However, over the last decade, the state of the art has been achieved by deep learning based approaches, and more precisely by Convolutional Neural Networks (CNNs) (Khan et al, 2016;Cohen et al, 2017;Xie et al, 2018a;Falk et al, 2019;Han et al, 2019;Xie et al, 2018b;Paulauskaite-Taraseviciene et al, 2019;Liu et al, 2019;Sierra et al, 2020;Zheng et al, 2020;He et al, 2021). In object counting, it is common to distinguish between detection-based methods (Arteta et al, 2016;Laradji et al, 2018;Xie et al, 2018b;Falk et al, 2019), which are designed to precisely locate objects before counting them, and regression-based methods (Cohen et al, 2017;Xie et al, 2018a;He et al, 2021), which directly output a number of cells without necessarily detecting their precise locations.…”