Papers › Sequential Hierarchical Learning with Distribution Transformation for Image Super-Resolution

Sequential Hierarchical Learning with Distribution Transformation for Image Super-Resolution

19 Jul 2020arXiv:2007.09552archive 2025-07-28

Yuqing Liu, Xinfeng Zhang, Shanshe Wang, Siwei Ma, Wen Gao

Multi-scale design has been considered in recent image super-resolution (SR) works to explore the hierarchical feature information. Existing multi-scale networks aim to build elaborate blocks or progressive architecture for restoration. In general, larger scale features concentrate more on structural and high-level information, while smaller scale features contain plentiful details and textured information. In this point of view, information from larger scale features can be derived from smaller ones. Based on the observation, in this paper, we build a sequential hierarchical learning super-resolution network (SHSR) for effective image SR. Specially, we consider the inter-scale correlations of features, and devise a sequential multi-scale block (SMB) to progressively explore the hierarchical information. SMB is designed in a recursive way based on the linearity of convolution with restricted parameters. Besides the sequential hierarchical learning, we also investigate the correlations among the feature maps and devise a distribution transformation block (DTB). Different from attention-based methods, DTB regards the transformation in a normalization manner, and jointly considers the spatial and channel-wise correlations with scaling and bias factors. Experiment results show SHSR achieves superior quantitative performance and visual quality to state-of-the-art methods with near 34\% parameters and 50\% MACs off when scaling factor is ×4. To boost the performance without further training, the extension model SHSR^+ with self-ensemble achieves competitive performance than larger networks with near 92\% parameters and 42\% MACs off with scaling factor ×4.

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Tasks

Image RestorationImage Super-ResolutionSSIMSuper-Resolution

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Image Super-Resolution Manga109 - 2x upscaling PMRN+ PSNR 39.15 #18 of 21 Archive leaderboard report
Image Super-Resolution Manga109 - 2x upscaling PMRN+ SSIM 0.9781 #18 of 21 Archive leaderboard report
Image Super-Resolution Manga109 - 3x upscaling PMRN+ PSNR 34.1 #15 of 17 Archive leaderboard report
Image Super-Resolution Manga109 - 3x upscaling PMRN+ SSIM 0.9480 #15 of 17 Archive leaderboard report
Image Super-Resolution Manga109 - 4x upscaling PMRN+ PSNR 31.07 #36 of 50 Archive leaderboard report
Image Super-Resolution Manga109 - 4x upscaling PMRN+ SSIM 0.9144 #36 of 50 Archive leaderboard report
Image Super-Resolution Set14 - 3x upscaling PMRN+ PSNR 29.24 #23 of 24 Archive leaderboard report
Image Super-Resolution Set14 - 3x upscaling PMRN+ SSIM 0.8087 #23 of 24 Archive leaderboard report
Image Super-Resolution Set14 - 4x upscaling PMRN+ PSNR 27.72 #86 of 104 Archive leaderboard report
Image Super-Resolution Set14 - 4x upscaling PMRN+ SSIM 0.7405 #86 of 104 Archive leaderboard report
Image Super-Resolution Set5 - 2x upscaling PMRN+ PSNR 38.22 #19 of 41 Archive leaderboard report
Image Super-Resolution Set5 - 2x upscaling PMRN+ SSIM 0.9612 #19 of 41 Archive leaderboard report
Image Super-Resolution Set5 - 3x upscaling PMRN+ PSNR 34.65 #20 of 32 Archive leaderboard report
Image Super-Resolution Set5 - 3x upscaling PMRN+ SSIM 0.9289 #20 of 32 Archive leaderboard report
Image Super-Resolution Urban100 - 2x upscaling PMRN+ PSNR 32.78 #21 of 29 Archive leaderboard report
Image Super-Resolution Urban100 - 2x upscaling PMRN+ SSIM 0.9342 #21 of 29 Archive leaderboard report

Ranks are positions in the archive's leaderboards as they stood at the 2025-07-28 snapshot. Results published since then are not among these rows, so a rank here is not a current standing.

Methods

Batch NormalizationConvolutionReLUResidual BlockResidual Connection

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