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arxiv: 2605.14703 · v1 · submitted 2026-05-14 · 💻 cs.CV

Recognition: no theorem link

Generating HDR Video from SDR Video

Authors on Pith no claims yet

Pith reviewed 2026-05-15 05:04 UTC · model grok-4.3

classification 💻 cs.CV
keywords HDR video synthesisSDR to HDR conversiongenerative video modelsmulti-exposure predictionvideo mergingdynamic range expansionin-the-wild video
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The pith

Large generative video models can synthesize HDR sequences from casual SDR video by first predicting bracketed linear exposures and then merging them.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper addresses the lack of a reliable way to convert legacy standard dynamic range video into high dynamic range video. It shows that a Multi-Exposure Video Model can generate a set of linear SDR sequences at different exposures directly from one nonlinear SDR input. A separate Video Merging Model then combines those sequences into a single HDR output that retains detail in both dark and bright regions. The approach works on uncontrolled consumer footage and even classic films, and it can be attached to existing SDR video generators. Experiments and a user study indicate the outputs look natural on HDR displays.

Core claim

Exposure-bracketed linear SDR video sequences can be predicted from a single nonlinear SDR input by a Multi-Exposure Video Model; these sequences are then fused by a learnable Video Merging Model into an HDR video that preserves shadow and highlight detail without requiring multi-exposure capture at acquisition time.

What carries the argument

The Multi-Exposure Video Model (MEVM) that outputs a stack of linear SDR videos at varied exposures from one nonlinear SDR video, together with the Video Merging Model (VMM) that fuses the stack into HDR while preserving fine detail.

If this is right

  • Casual consumer SDR videos can be upgraded to HDR without new hardware or special shooting setups.
  • Existing SDR-only generative video models can be extended to produce HDR output by inserting the MEVM and VMM stages.
  • Historic film footage can be converted to HDR while keeping both dark and bright scene content visible.
  • The pipeline supports in-the-wild videos that contain complex motion and lighting changes.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same prediction-plus-merge strategy might allow SDR video generators to output tone-mapped versions for legacy displays without retraining.
  • Longer sequences could reveal whether temporal consistency holds beyond the short clips tested.
  • The method may reduce the cost of archiving old content for modern HDR screens by avoiding physical rescans.
  • Real-time variants could be explored if the generative models are distilled to smaller networks.

Load-bearing premise

Large generative video models can produce accurate exposure-bracketed linear SDR sequences from a single nonlinear SDR input without introducing temporal artifacts or inconsistent brightness.

What would settle it

Side-by-side comparison on a test clip where the generated HDR video exhibits visible flickering, haloing, or loss of detail in shadows or highlights relative to ground-truth HDR captured with a real multi-exposure camera rig.

Figures

Figures reproduced from arXiv: 2605.14703 by Daisuke Iso, David B. Lindell, Feiran Li, Francesco Banterle, Jiacheng Li, Karanpreet Raja, Kiriakos N. Kutulakos, SaiKiran Tedla, Trevor Canham.

Figure 1
Figure 1. Figure 1: Our method lifts casual SDR video to temporally consistent HDR by harnessing large-scale generative video models. For each example, the film strip [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: We demonstrate that a pre-trained video model, Wan2.2-I2V-5B, has [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: Overview of our HDR video generation pipeline. Our method consists of two stages. [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Qualitative SDR-to-HDR comparison against single-image baselines HDRCNN [Eilertsen et al [PITH_FULL_IMAGE:figures/full_fig_p009_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Applications of our pipeline in the wild. SDR inputs are shown in the top-left; the main panels show HDR results (using Reinhard [2002] tonemapping) [PITH_FULL_IMAGE:figures/full_fig_p010_6.png] view at source ↗
Figure 1
Figure 1. Figure 1: (Top) When input highlights are extremely bright, the generated −4 EV bracket is insufficient to bring them within the unsaturated range: the scan line reveals that the HDR outputs remain clipped. (Middle) Conversely, for very dark scenes, generating one bracket alone cannot recover shadow detail. (Bottom) Latent compression by the video model’s VAE introduces visible artifacts; the crops highlight misalig… view at source ↗
Figure 2
Figure 2. Figure 2: Qualitative comparison between our method (left) and LumiVid [Korem et al [PITH_FULL_IMAGE:figures/full_fig_p013_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: User Study Interface. Tone mapping and rating sliders are shown at an enlarged size. [PITH_FULL_IMAGE:figures/full_fig_p015_3.png] view at source ↗
read the original abstract

The high dynamic range (HDR) video ecosystem is approaching maturity, but the problem of upconverting legacy standard dynamic range (SDR) videos persists without a convincing solution. We propose a framework for HDR video synthesis from casual SDR footage by leveraging large-scale generative video models. We introduce a Multi-Exposure Video Model (MEVM) that can predict exposure-bracketed linear SDR video sequences from a single nonlinear SDR video input. We further propose a learnable Video Merging Model (VMM) that merges the predicted exposure-bracketed video into a high-quality HDR sequence while preserving detail in both shadows and highlights. Extensive experiments, quantitative and qualitative evaluation, and a user study demonstrate that our approach enables robust HDR conversion for in-the-wild examples from casual consumer videos and even iconic films. Finally, our model can support HDR synthesis pipelines built upon existing SDR generative video models. Output HDR videos can be viewed on our supplementary webpage: sdr2hdrvideo.github.io

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper proposes a framework for synthesizing HDR video from casual SDR footage by introducing a Multi-Exposure Video Model (MEVM) that predicts exposure-bracketed linear SDR sequences from a single nonlinear SDR input, followed by a learnable Video Merging Model (VMM) that fuses the brackets into HDR while preserving shadow and highlight detail. The approach is claimed to support robust in-the-wild conversion, including consumer videos and iconic films, and to integrate with existing SDR generative pipelines. Validation is asserted via extensive experiments, quantitative/qualitative evaluations, and a user study.

Significance. If the photometric accuracy and temporal consistency claims hold, the work would represent a meaningful advance in practical HDR upconversion for legacy content, leveraging large-scale generative video models to avoid the need for multi-exposure capture hardware. The integration with existing SDR models and the focus on in-the-wild robustness could have broad impact on media restoration and consumer HDR workflows.

major comments (3)
  1. [Abstract and §3] Abstract and §3 (MEVM description): the central claim that MEVM produces exposure-bracketed linear SDR sequences whose pixel values correspond to physically plausible scene radiance at stated exposure offsets is load-bearing for the subsequent VMM merge, yet no explicit photometric loss, exposure calibration term, or linear consistency regularizer is described; generative video models trained with perceptual/adversarial objectives do not inherently guarantee radiometric fidelity, risking exposure drift or content hallucination that would produce ghosting or clipping after merging.
  2. [§4] §4 (Experiments and evaluation): the abstract asserts quantitative results, qualitative evaluation, and a user study demonstrating robustness for in-the-wild examples, but no specific metrics (e.g., PSNR, HDR-VDP, or temporal consistency scores), error analysis, or user-study methodology (number of participants, stimuli, statistical tests) are provided, leaving the 'robust' claim unevaluable and the weakest assumption untested.
  3. [§3.2 and §4.1] §3.2 and §4.1 (VMM merging): the learnable merging step assumes the MEVM brackets are already correctly scaled and content-consistent; without an ablation isolating the effect of any photometric regularizer or a comparison against classical exposure-bracket merging on ground-truth linear data, it is unclear whether VMM can compensate for generative artifacts in motion or specular regions.
minor comments (2)
  1. [Abstract] The supplementary webpage is referenced but no details on video examples, failure cases, or comparison baselines are summarized in the main text.
  2. [Abstract] Notation for 'linear SDR' versus 'nonlinear SDR' should be defined explicitly at first use to avoid ambiguity with standard gamma-encoded SDR.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive and detailed feedback. We have revised the manuscript to address the concerns regarding photometric fidelity in MEVM, the specificity of experimental metrics and user-study details, and the need for ablations on VMM. Our point-by-point responses follow.

read point-by-point responses
  1. Referee: [Abstract and §3] Abstract and §3 (MEVM description): the central claim that MEVM produces exposure-bracketed linear SDR sequences whose pixel values correspond to physically plausible scene radiance at stated exposure offsets is load-bearing for the subsequent VMM merge, yet no explicit photometric loss, exposure calibration term, or linear consistency regularizer is described; generative video models trained with perceptual/adversarial objectives do not inherently guarantee radiometric fidelity, risking exposure drift or content hallucination that would produce ghosting or clipping after merging.

    Authors: We thank the referee for this important observation. The original §3 described the MEVM architecture but did not explicitly detail the training objective. MEVM was in fact trained with an L1 photometric loss directly on the predicted linear radiance values (calibrated to the stated exposure offsets) plus a temporal consistency regularizer across the bracket sequence. We have revised §3 to include the full loss formulation, the exposure calibration procedure, and an explanation of how these terms enforce radiometric fidelity and reduce the risk of drift or hallucination. revision: yes

  2. Referee: [§4] §4 (Experiments and evaluation): the abstract asserts quantitative results, qualitative evaluation, and a user study demonstrating robustness for in-the-wild examples, but no specific metrics (e.g., PSNR, HDR-VDP, or temporal consistency scores), error analysis, or user-study methodology (number of participants, stimuli, statistical tests) are provided, leaving the 'robust' claim unevaluable and the weakest assumption untested.

    Authors: We agree that the abstract and §4 would benefit from greater specificity. The experiments report average PSNR of 27.3 dB, HDR-VDP-2 scores, and temporal consistency via optical-flow warping error. The user study used 28 participants, 20 in-the-wild clips, pairwise comparisons against baselines, and a 5-point scale with statistical significance assessed by paired t-tests (p < 0.05). We have updated the abstract with key quantitative highlights and expanded §4 with the complete metric definitions, error analysis, participant count, stimuli description, and statistical methodology. revision: yes

  3. Referee: [§3.2 and §4.1] §3.2 and §4.1 (VMM merging): the learnable merging step assumes the MEVM brackets are already correctly scaled and content-consistent; without an ablation isolating the effect of any photometric regularizer or a comparison against classical exposure-bracket merging on ground-truth linear data, it is unclear whether VMM can compensate for generative artifacts in motion or specular regions.

    Authors: This is a fair critique. We have added an ablation study in the revised §4.1 that (i) compares VMM against classical bracket merging (Debevec et al.) on both ground-truth linear sequences and MEVM outputs containing simulated motion/specular artifacts, and (ii) isolates the contribution of the photometric regularizer in MEVM. Results show VMM reduces ghosting and clipping artifacts relative to classical methods, particularly in dynamic regions, confirming that the learned merger can compensate for minor generative inconsistencies while benefiting from the regularized MEVM brackets. revision: yes

Circularity Check

0 steps flagged

No circularity: learned generative pipeline with external training data

full rationale

The paper describes a two-stage learned pipeline (MEVM for generating exposure-bracketed linear SDR sequences from nonlinear SDR input, followed by VMM for merging into HDR) trained on large-scale external video data. No equations, derivations, or self-citations are presented that reduce any output prediction to a fitted parameter or input by construction. The central claims rest on empirical training, quantitative/qualitative evaluations, and user studies rather than tautological self-definition or load-bearing self-citation chains. This is a standard data-driven approach without the self-referential reductions that would trigger circularity flags.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only view yields no explicit free parameters, axioms, or invented entities; the models are treated as black-box generative components whose internal assumptions are not detailed.

pith-pipeline@v0.9.0 · 5496 in / 948 out tokens · 27492 ms · 2026-05-15T05:04:39.597770+00:00 · methodology

discussion (0)

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