arXiv:2501.17898eess.IVcs.LG2025-01被引 3

用教师模型指导受限成像系统设计,提升重建效果。

Distilling Knowledge for Designing Computational Imaging Systems

  • 用放松约束的教师模型指导物理受限的成像系统设计。
  • 在三种成像模态上均显著优于端到端优化和传统方法。
  • 适用于各类成像场景,可灵活适配不同采集与解码器。

在计算成像(CI)系统中,物理编码器的设计对图像重建精度至关重要。当前方法采用端到端(E2E)优化,将编码器建模为神经网络层,并与解码器联合优化,但受物理约束影响,性能下降,且反向传播导致梯度消失,难以优化中间特征。为此,本文重新诠释知识蒸馏(KD)思想,通过预训练的、约束更少的教师系统向学生系统传递知识。方法包括:(1)在原系统(学生)基础上,放松编码器约束构建教师系统;(2)优化教师系统以解决简化版问题;(3)通过两种新提出的知识迁移函数,分别在编码器和解码器特征空间引导学生训练。该方法可适配多种成像模态,已在磁共振、单像素和压缩光谱成像三类典型场景验证。仿真结果表明,结构相似的教师编码器能有效引导学生,显著提升重建性能与编码器设计质量,优于E2E优化与非数据驱动的传统设计。

原文摘要 · Abstract (English)

Designing the physical encoder is crucial for accurate image reconstruction in computational imaging (CI) systems. Currently, these systems are designed via end-to-end (E2E) optimization, where the encoder is modeled as a neural network layer and is jointly optimized with the decoder. However, the performance of E2E optimization is significantly reduced by the physical constraints imposed on the encoder. Also, since the E2E learns the parameters of the encoder by backpropagating the reconstruction error, it does not promote optimal intermediate outputs and suffers from gradient vanishing. To address these limitations, we reinterpret the concept of knowledge distillation (KD) for designing a physically constrained CI system by transferring the knowledge of a pretrained, less-constrained CI system. Our approach involves three steps: (1) Given the original CI system (student), a teacher system is created by relaxing the constraints on the student's encoder. (2) The teacher is optimized to solve a less-constrained version of the student's problem. (3) The teacher guides the training of the student through two proposed knowledge transfer functions, targeting both the encoder and the decoder feature space. The proposed method can be employed to any imaging modality since the relaxation scheme and the loss functions can be adapted according to the physical acquisition and the employed decoder. This approach was validated on three representative CI modalities: magnetic resonance, single-pixel, and compressive spectral imaging. Simulations show that a teacher system with an encoder that has a structure similar to that of the student encoder provides effective guidance. Our approach achieves significantly improved reconstruction performance and encoder design, outperforming both E2E optimization and traditional non-data-driven encoder designs.

计算成像知识蒸馏图像重建

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