Deep Neural Networks' Geometric Blind Spot: Fourier Shapes for Enhanced Interpretability & Advers...

By Jian Wang, Yixing Yong, Haixia Bi, Lijun He, Fan Li


Published on November 10, 2025| Vol. 1, Issue No. 1

Summary\

Deep neural networks (DNNs) typically prioritize texture over shape in visual recognition, leading to a poor understanding of their geometric perception. This research introduces a novel, end-to-end differentiable framework that utilizes Fourier series to precisely parameterize arbitrary shapes, which are then translated into pixel grids for DNN input via a winding number-based mapping. The study reveals three critical insights: optimized shapes can act as potent semantic carriers, eliciting high-confidence classifications purely from geometry; they serve as high-fidelity interpretability tools, accurately isolating salient regions within a model; and they establish a new, generalizable paradigm for adversarial attacks that can deceive downstream visual tasks. This versatile framework provides new capabilities for probing DNNs' geometric understanding and advancing the field of machine perception.
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Why It Matters\

This research delves into a foundational limitation of deep neural networks: their often-demonstrated struggle with abstract geometric reasoning, favoring superficial textural cues. For AI professionals, these findings carry significant weight across multiple domains. Firstly, the revelation that optimized shapes can function as powerful semantic carriers implies that DNNs, despite their texture bias, can be highly sensitive to pure geometric information. This is a critical insight for developing more robust and human-like perception systems, moving beyond superficial pattern matching to a deeper understanding of object structure.

Secondly, the framework offers a novel and precise approach to explainable AI (XAI). By isolating salient regions using shape-based inputs, practitioners gain a more granular and potentially more actionable understanding of what features a model is truly attending to. This is invaluable for debugging model failures, ensuring fairness, and building trust in AI applications, especially in high-stakes fields like autonomous vehicles or medical diagnostics where misinterpretations have severe consequences.

Finally, the development of a generalizable adversarial paradigm rooted in shape manipulation highlights a significant vulnerability. If AI systems can be deceived by subtle geometric alterations, it poses a direct threat to their reliability and security in real-world deployments. Professionals in AI safety and security must take heed, as this work suggests new avenues for crafting sophisticated attacks but also for developing more resilient defensive strategies. The underlying trend here is the imperative to bridge the gap between statistical pattern recognition and genuine, common-sense understanding in AI. This paper doesn't just identify a problem; it provides both the tools to deeply probe it and the mechanisms to exploit it, pushing the AI community towards building systems that are not only accurate but also truly intelligent and trustworthy.

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