The task is to localize an image region described by natural language, which involves comprehending and modeling different spatial contexts, such as spatial configurations , attributes (Yu et al., 2018), and relationships between objects (Hu et al., 2017).
the task is usually formulated as a ranking problem over a set of candidate regions in a given image, where candidate spatial locations come from region proposal methods (Uijlings et al., 2013;Jie et al., 2016b,a;Ren et al., 2017) such as Edge-Box (Zitnick and Dollár, 2014).