用变分自编码器指导测量选择,少测几步就能还原完整数据。
Actively Inferring Optimal Measurement Sequences
- 基于VAE潜空间动态选下一步测量点,减少冗余采样。
- 10步内选出有效测量模式,生成图像快速收敛。
- 适合数据稀缺或测量成本高的场景,如医学成像。
物理量(如光强度)的测量在重建与决策中不可或缺,但常耗费时间、造成环境干扰或损害,且需满足数据最小化与隐私保护要求。当存在多种可选测量方式时,部分测量更高效且符合目标。本文提出一种主动序列推断算法,利用变分自编码器(VAE)的低维潜空间来决定下一步测量。通过将部分测量数据映射至完整数据的潜空间,算法生成条件数据并估算新测量值,再反馈至潜空间评估,逐步更新后验分布。从无测量和标准先验开始,比较不同策略选择下一测量并更新预测后验。实验采用Fashion MNIST数据集与新型卷积哈达玛德模式测量基,结果表明10步内即选出有效模式,引导生成图像快速收敛。相比对每个生成数据点单独使用随机变分推断,该部分VAE框架能高效处理批量数据,以最少测量实现更优恢复效果。
原文摘要 · Abstract (English)
Measurement of a physical quantity such as light intensity is an integral part of many reconstruction and decision scenarios but can be costly in terms of acquisition time, invasion of or damage to the environment and storage. Data minimisation and compliance with data protection laws is also an important consideration. Where there are a range of measurements that can be made, some may be more informative and compliant with the overall measurement objective than others. We develop an active sequential inference algorithm that uses the low dimensional representational latent space from a variational autoencoder (VAE) to choose which measurement to make next. Our aim is to recover high dimensional data by making as few measurements as possible. We adapt the VAE encoder to map partial data measurements on to the latent space of the complete data. The algorithm draws samples from this latent space and uses the VAE decoder to generate data conditional on the partial measurements. Estimated measurements are made on the generated data and fed back through the partial VAE encoder to the latent space where they can be evaluated prior to making a measurement. Starting from no measurements and a normal prior on the latent space, we consider alternative strategies for choosing the next measurement and updating the predictive posterior prior for the next step. The algorithm is illustrated using the Fashion MNIST dataset and a novel convolutional Hadamard pattern measurement basis. We see that useful patterns are chosen within 10 steps, leading to the convergence of the guiding generative images. Compared with using stochastic variational inference to infer the parameters of the posterior distribution for each generated data point individually, the partial VAE framework can efficiently process batches of generated data and obtains superior results with minimal measurements.
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