arXiv:2503.24271astro-ph.SRastro-ph.IM2025-03中稿 · publication on A&A被引 2

用扩散模型提升太阳磁图分辨率,让老数据达到新仪器水平。

Enhancing Image Resolution of Solar Magnetograms: A Latent Diffusion Model Approach

  • 基于残差的潜空间扩散模型,从2角秒/像素升到0.5角秒/像素。
  • 重建后图像在PSNR、SSIM等指标上优于传统方法,物理量保持一致。
  • 适合研究太阳活动区、耀斑等小尺度现象的科研人员使用。

太阳磁场的空间特性对理解太阳内部物理过程及其行星际影响至关重要。然而,早期仪器(如米歇尔森多普勒成像仪,MDI)的观测分辨率有限,难以细致研究小尺度太阳特征。对这些旧数据进行超分辨处理,对于跨太阳周期的统一分析具有重要意义,有助于更准确刻画太阳耀斑、活动区及磁网络动力学。本文提出一种新型扩散模型方法,应用于MDI磁图以匹配日震与磁成像仪(HMI)的高分辨率能力。通过在降采样的HMI数据上训练带残差的潜空间扩散模型(LDM),并用配对的MDI/HMI数据微调,成功将MDI图像分辨率从2″/像素提升至0.5″/像素。我们采用经典指标(如PSNR、SSIM、FID、LPIPS)评估重建质量,并验证了无符号磁通量、活动区尺寸等物理特性是否保留。相比多种LDM变体、去噪扩散概率模型(DDPM)及以往确定性架构,本方法表现更优。傅里叶域分析表明,该模型可解析小于2″的结构,且因其概率特性,能评估结果可靠性,优于确定性模型。未来工作将拓展时间维度超分辨,实现对旧事件动态过程的更好把握。

原文摘要 · Abstract (English)

The spatial properties of the solar magnetic field are crucial to decoding the physical processes in the solar interior and their interplanetary effects. However, observations from older instruments, such as the Michelson Doppler Imager (MDI), have limited spatial or temporal resolution, which hinders the ability to study small-scale solar features in detail. Super resolving these older datasets is essential for uniform analysis across different solar cycles, enabling better characterization of solar flares, active regions, and magnetic network dynamics. In this work, we introduce a novel diffusion model approach for Super-Resolution and we apply it to MDI magnetograms to match the higher-resolution capabilities of the Helioseismic and Magnetic Imager (HMI). By training a Latent Diffusion Model (LDM) with residuals on downscaled HMI data and fine-tuning it with paired MDI/HMI data, we can enhance the resolution of MDI observations from 2"/pixel to 0.5"/pixel. We evaluate the quality of the reconstructed images by means of classical metrics (e.g., PSNR, SSIM, FID and LPIPS) and we check if physical properties, such as the unsigned magnetic flux or the size of an active region, are preserved. We compare our model with different variations of LDM and Denoising Diffusion Probabilistic models (DDPMs), but also with two deterministic architectures already used in the past for performing the Super-Resolution task. Furthermore, we show with an analysis in the Fourier domain that the LDM with residuals can resolve features smaller than 2", and due to the probabilistic nature of the LDM, we can asses their reliability, in contrast with the deterministic models. Future studies aim to super-resolve the temporal scale of the solar MDI instrument so that we can also have a better overview of the dynamics of the old events.

图像超分扩散模型太阳物理

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