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Polarity Loss: Improving Visual-Semantic Alignment for Zero-Shot Detection
IEEE Transactions on Neural Networks and Learning Systems
  • Shafin Rahman, Department of Electrical and Computer Engineering, North South University, Dhaka, Bangladesh
  • Salman Khan, Mohamed bin Zayed University of Artificial Intelligence
  • Nick Barnes, School of Computing, The Australian National University, Canberra, ACT, Australia
Document Type

Conventional object detection models require large amounts of training data. In comparison, humans can recognize previously unseen objects by merely knowing their semantic description. To mimic similar behavior, zero-shot object detection (ZSD) aims to recognize and localize “unseen” object instances by using only their semantic information. The model is first trained to learn the relationships between visual and semantic domains for seen objects, later transferring the acquired knowledge to totally unseen objects. This setting gives rise to the need for correct alignment between visual and semantic concepts so that the unseen objects can be identified using only their semantic attributes. In this article, we propose a novel loss function called “polarity loss” that promotes correct visual-semantic alignment for an improved ZSD. On the one hand, it refines the noisy semantic embeddings via metric learning on a “semantic vocabulary” of related concepts to establish a better synergy between visual and semantic domains. On the other hand, it explicitly maximizes the gap between positive and negative predictions to achieve better discrimination between seen, unseen, and background objects. Our approach is inspired by embodiment theories in cognitive science that claim human semantic understanding to be grounded in past experiences (seen objects), related linguistic concepts (word vocabulary), and visual perception (seen/unseen object images). We conduct extensive evaluations on the Microsoft Common Objects in Context (MS-COCO) and Pascal Visual Object Classes (VOC) datasets, showing significant improvements over state of the art. Our code and evaluation protocols available at: IEEE

Publication Date
  • Computer vision,
  • Deep neural networks,
  • Function evaluation,
  • Object detection,
  • Object recognition,
  • Zero-shot learning,
  • Loss functions,
  • Noise measurements,
  • Objects detection,
  • Semantic alignments,
  • Visual semantics,
  • Vocabulary,
  • Zero-shot learning,
  • Zero-shot object detection,
  • Semantics

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OA version (pathway a) Accepted version

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Citation Information
S. Rahman, S. Khan and N. Barnes, "Polarity Loss: Improving Visual-Semantic Alignment for Zero-Shot Detection," in IEEE Transactions on Neural Networks and Learning Systems, 2022, doi: 10.1109/TNNLS.2022.3184821.