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arXiv 2603.16134cs.CVcs.AIcs.LG

生成增强有害:GAN和扩散模型在AI分类系统中的偏见校正基准研究

When Generative Augmentation Hurts: A Benchmark Study of GAN and Diffusion Models for Bias Correction in AI Classification Systems

College of Engineering, Northeastern University(东北大学工程学院)

Shesh Narayan Gupta, Nik Bear Brown

AI总结:

本文通过对比三种增强策略,发现生成增强在低数据条件下会增加分类器偏见,Stable Diffusion结合LoRA表现最佳,揭示了GAN增强在特定样本量下的有害性。

摘要:

生成模型被广泛用于补偿AI训练管道中的类别不平衡,但其在低数据条件下的失败模式尚不明确。本文报告了一项受控基准测试,比较了三种增强策略应用于细粒度动物分类任务:传统变换、FastGAN和Stable Diffusion 1.5结合LoRA。使用包含八个人工低估品种的Oxford-IIIT宠物数据集,发现FastGAN增强不仅在极低训练集大小下表现不佳,而且会主动增加分类器偏见,统计学上显著(偏见差距增加:+20.7%,Cohen's d = +5.03,p = 0.013)。特征嵌入分析显示,FastGAN生成的严重少数族裔图像形成紧密孤立簇,与真实图像分布不一致,符合模式崩溃。Stable Diffusion结合LoRA整体表现最佳,实现了最高的宏F1(0.9125±0.0047)和13.1%的偏见差距减少。数据表明样本量边界在20到50个训练图像之间,但需进一步研究以确定精确位置。所有实验在消费级GPU上运行,内存为6到8GB,无需云计算。

英文摘要:

Generative models are widely used to compensate for class imbalance in AI training pipelines, yet their failure modes under low-data conditions are poorly understood. This paper reports a controlled benchmark comparing three augmentation strategies applied to a fine-grained animal classification task: traditional transforms, FastGAN, and Stable Diffusion 1.5 fine-tuned with Low-Rank Adaptation (LoRA). Using the Oxford-IIIT Pet Dataset with eight artificially underrepresented breeds, we find that FastGAN augmentation does not merely underperform at very low training set sizes but actively increases classifier bias, with a statistically significant large effect across three random seeds (bias gap increase: +20.7%, Cohen's d = +5.03, p = 0.013). The effect size here is large enough to give confidence in the direction of the finding despite the small number of seeds. Feature embedding analysis using t-distributed Stochastic Neighbor Embedding reveals that FastGAN images for severe-minority breeds form tight isolated clusters outside the real image distribution, a pattern consistent with mode collapse. Stable Diffusion with Low-Rank Adaptation produced the best results overall, achieving the highest macro F1 (0.9125 plus or minus 0.0047) and a 13.1% reduction in the bias gap relative to the unaugmented baseline. The data suggest a sample-size boundary somewhere between 20 and 50 training images per class below which GAN augmentation becomes harmful in this setting, though further work across additional domains is needed to establish where that boundary sits more precisely. All experiments run on a consumer-grade GPU with 6 to 8 GB of memory, with no cloud compute required.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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