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arxiv: 2604.11395 · v1 · submitted 2026-04-13 · 💻 cs.CV

Video-based Heart Rate Estimation with Angle-guided ROI Optimization and Graph Signal Denoising

Pith reviewed 2026-05-10 15:43 UTC · model grok-4.3

classification 💻 cs.CV
keywords rPPGremote photoplethysmographyheart rate estimationmotion artifactsgraph signal processingROI optimizationfacial video analysisdenoising
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The pith

Two plug-and-play modules using ROI-camera angles and graph signal processing reduce errors in video-based heart rate measurement during motion.

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

The paper introduces two modules to make remote photoplethysmography more robust to facial motions like speaking and head shaking. One module quantifies the angles between selected facial regions and the camera to refine affected signals and capture overall movement. The other module treats multiple regions as a graph and applies joint signal processing to remove motion noise while keeping physiological information. When added to existing reflection-based rPPG methods, the pair lowers average mean absolute error by 20.38 percent across three public datasets. A reader would care because reliable non-contact heart rate tracking becomes feasible in everyday settings without requiring subjects to stay still.

Core claim

The central claim is that the Angle-guided ROI Adaptive Optimization module, which quantifies ROI-Camera angles to refine motion-affected signals and capture global motion, combined with the Multi-region Joint Graph Signal Denoising module, which jointly models intra- and inter-regional ROI signals using graph signal processing to suppress motion artifacts, produces markedly lower mean absolute error when integrated with reflection model-based rPPG methods.

What carries the argument

The two plug-and-play modules: angle-guided ROI adaptive optimization that quantifies camera angles to adjust signals, and multi-region joint graph signal denoising that models relationships across facial regions to filter artifacts.

If this is right

  • The modules integrate directly with existing reflection model-based rPPG methods without retraining.
  • Performance gains hold across three public datasets containing speaking and head-shaking motions.
  • Ablation tests show each module contributes independently to the overall error reduction.
  • The approach supports more practical deployment of video heart rate estimation in motion-heavy environments.

Where Pith is reading between the lines

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

  • The same angle and graph techniques could be tested on other remote vital-sign tasks such as respiration rate from video.
  • Extending the graph to include temporal edges across video frames might further stabilize estimates during prolonged motion.
  • The method may lower the barrier to using rPPG in telemedicine or fitness applications where subjects move naturally.

Load-bearing premise

That quantifying ROI-Camera angles accurately captures and mitigates motion artifacts without introducing new biases, and that the graph denoising preserves true physiological signals across regions.

What would settle it

Apply the modules to a dataset with simultaneous ECG ground truth and known extreme head motions, then disable the angle quantification or graph edges and check whether the 20 percent MAE reduction disappears or reverses.

read the original abstract

Remote photoplethysmography (rPPG) enables non-contact heart rate measurement from facial videos, but its performance is significantly degraded by facial motions such as speaking and head shaking. To address this issue, we propose two plug-and-play modules. The Angle-guided ROI Adaptive Optimization module quantifies ROI-Camera angles to refine motion-affected signals and capture global motion, while the Multi-region Joint Graph Signal Denoising module jointly models intra- and inter-regional ROI signals using graph signal processing to suppress motion artifacts. The modules are compatible with reflection model-based rPPG methods and validated on three public datasets. Results show that jointly use markedly reduces MAE, with an average decrease of 20.38\% over the baseline, while ablation studies confirm the effectiveness of each module. The work demonstrates the potential of angle-guided optimization and graph-based denoising to enhance rPPG performance in motion scenarios.

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

1 major / 2 minor

Summary. The paper proposes two plug-and-play modules to improve remote photoplethysmography (rPPG) heart rate estimation from facial videos under motion artifacts: an Angle-guided ROI Adaptive Optimization module that quantifies ROI-camera angles to refine motion-affected signals and capture global motion, and a Multi-region Joint Graph Signal Denoising module that jointly models intra- and inter-regional ROI signals via graph signal processing to suppress artifacts. These modules are presented as compatible with existing reflection model-based rPPG methods and are evaluated on three public datasets, with the joint use claimed to reduce MAE by an average of 20.38% over baseline, supported by ablation studies confirming each module's contribution.

Significance. If the empirical MAE reductions are reproducible with full experimental details, the work offers a practical, modular approach to mitigating motion artifacts in non-contact HR estimation, potentially improving robustness in real-world scenarios like speaking or head shaking. The angle-guided and graph-based techniques provide a distinct perspective on ROI optimization and signal denoising, with the plug-and-play design facilitating adoption; however, the current lack of verification details limits assessment of broader impact.

major comments (1)
  1. The abstract and experimental sections report a 20.38% average MAE reduction and ablation results but omit key details on data splits, error bars, statistical significance tests, and exact hyperparameter choices or post-hoc selections; these omissions directly limit verification of the central empirical claim and the weakest assumption that angle quantification and graph denoising mitigate artifacts without introducing bias.
minor comments (2)
  1. Notation for ROI angles and graph construction in the method description could be clarified with explicit equations or pseudocode to improve reproducibility.
  2. Figure captions and table legends should explicitly state the baseline methods and dataset motion conditions for easier cross-reference with the reported improvements.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive review and positive recommendation for minor revision. We agree that additional details are needed to support reproducibility and verification of our empirical claims, and we will incorporate them in the revised manuscript.

read point-by-point responses
  1. Referee: The abstract and experimental sections report a 20.38% average MAE reduction and ablation results but omit key details on data splits, error bars, statistical significance tests, and exact hyperparameter choices or post-hoc selections; these omissions directly limit verification of the central empirical claim and the weakest assumption that angle quantification and graph denoising mitigate artifacts without introducing bias.

    Authors: We appreciate this feedback and fully acknowledge that the current version lacks sufficient details for independent verification. In the revised manuscript, we will expand the experimental section (and update the abstract if space allows) to include: (1) explicit descriptions of the data splits used for each of the three public datasets, including whether they are subject-independent; (2) error bars (mean ± standard deviation) for all MAE results, computed across subjects or multiple runs; (3) statistical significance tests such as paired t-tests or Wilcoxon signed-rank tests with p-values comparing our full method and ablations against baselines; and (4) a dedicated table listing all hyperparameters with exact values, ranges, and the selection procedure (including any post-hoc choices). Regarding the assumption of no introduced bias, the Angle-guided ROI Adaptive Optimization module uses geometric angle quantification solely to select and weight ROIs for better motion capture, without altering signal amplitudes or introducing systematic shifts. The Multi-region Joint Graph Signal Denoising module applies graph-based low-pass filtering to suppress high-frequency motion components while preserving the low-frequency physiological signal, as validated by our frequency-domain analysis. Ablation results already show gains in motion scenarios without degradation on low-motion subsets, supporting that bias is not introduced. We will add an explicit discussion subsection on bias analysis and mitigation in the revision. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper proposes two empirical plug-and-play modules (angle-guided ROI optimization and multi-region graph signal denoising) as compatible additions to existing reflection-model rPPG methods. Its central claims rest on experimental MAE reductions (20.38% average) and ablations across three public datasets under motion conditions, not on any mathematical derivation, first-principles prediction, or self-referential definition. No equations or steps reduce by construction to fitted inputs, self-citations, or renamed known results; the argument structure is self-contained via external dataset validation and does not invoke load-bearing uniqueness theorems or ansatzes from prior author work.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review provides no identifiable free parameters, axioms, or invented entities; modules are framed as plug-and-play extensions without new postulated entities.

pith-pipeline@v0.9.0 · 5457 in / 943 out tokens · 23595 ms · 2026-05-10T15:43:21.408226+00:00 · methodology

discussion (0)

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Reference graph

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    INTRODUCTION Remote photoplethysmography (rPPG) is a non-contact, non- invasive, and cost-efficient optical technique that derives blood volume pulse (BVP) signals from skin regions in RGB video [1]. It enables the estimation of vital signs such as heart rate (HR) and respiration, with broad applicability in telemedicine, continuous health monitoring, and...

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    Angle-guided ROI Adaptive Optimization The Pipeline of the proposed method is illustrated in Fig

    METHOD 2.1. Angle-guided ROI Adaptive Optimization The Pipeline of the proposed method is illustrated in Fig. 2. MediaPipe provides dense 3D coordinates of 468 facial land- marks. Leveraging facial midline symmetry, 60 landmarks are selected on the forehead, cheeks, and chin; for each selected landmark, a20×20-pixel rectangular ROI is con- structed center...

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    Performance comparison of baseline rPPG methods with angle-guided ROI module (AGROI) and multi-region joint graph signal denoising module (GSD) on three pub- lic datasets

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