  This paper introduces a method for image semantic segmentation grounded on a
novel fusion scheme, which takes place inside a deep convolutional neural
network. The main goal of our proposal is to explore object boundary
information to improve the overall segmentation performance. Unlike previous
works that combine boundary and segmentation features, or those that use
boundary information to regularize semantic segmentation, we instead propose a
novel approach that embodies boundary information onto segmentation. For that,
our semantic segmentation method uses two streams, which are combined through
an attention gate, forming an end-to-end Y-model. To the best of our knowledge,
ours is the first work to show that boundary detection can improve semantic
segmentation when fused through a semantic fusion gate (attention model). We
performed an extensive evaluation of our method over public data sets. We found
competitive results on all data sets after comparing our proposed model with
other twelve state-of-the-art segmenters, considering the same training
conditions. Our proposed model achieved the best mIoU on the CityScapes,
CamVid, and Pascal Context data sets, and the second best on Mapillary Vistas.
