Real-Time Diffusion Relighting as a Neural Sensor:
Closing the Low-Light Domain Gap for Robotic Perception

Shengjie Xu1, Alexander Gao1, Anshul Rai2, Dae Yeol Lee2, Guan-Ming Su2, Ming C. Lin1
1University of Maryland, College Park   2Dolby Laboratories
IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) 2026
CARLA night raw camera
Night camera (raw)
CARLA night relit by neural sensor
Generative neural sensor

Treat illumination as a generative prior, not a signal-processing filter— then run the heavy model as an asynchronous sensor inside the control loop.

Abstract

Low-light conditions severely degrade robotic perception: object detectors trained on daylight imagery fail under fog and darkness, yet existing Low-Light Image Enhancement (LLIE) methods are designed for offline processing and cannot integrate into live control loops. We identify a critical deployment gap—no prior work runs a large generative model as a real-time sensor inside a control loop.

We introduce a Generative Neural Sensor that treats illumination as a generative prior rather than a signal processing problem, enabling task-relevant semantic recovery. An Asynchronous Perceptual Architecture decouples high-latency semantic recovery from low-latency vehicle control, isolating a rectified-flow transformer and illumination adapter in a background thread. Uncertainty-aware activation triggers enhancement only when detection confidence drops, treating generative compute as a sparse resource.

87.1%
ExDark mean AP
(+10.5 vs. IROS 2025 SOTA)
0.855
vKITTI2 Fog F1
(+0.174 over baseline)
100%
CARLA lap completion
with closed-loop control

TL;DR. Pixel-reconstruction LLIE can erase the edges detectors need. Generative semantic recovery + async, confidence-triggered deployment closes the low-light domain gap for live robotic control.

Key Findings

Semantic priors beat pixel reconstruction. On ExDark, our method leads all 12 categories (87.1% mAP). On vKITTI2 fog, MambaSFLNet falls below the unenhanced baseline (F1 0.579), while generative recovery reaches F1 0.855.

Async neural sensing. A large diffusion model need not block the 20 Hz control loop: isolate it in a background thread and feed the latest relit manifold to detection.

Uncertainty-aware activation. At sunset, event-driven triggering relights only 0.4% of frames, cutting GPU utilization from 95% to 0.4% while also reducing collisions— gating avoids unnecessary generative artifacts.

Closed-loop safety. On Thunderhill in CARLA, generative sensing restores near-daylight collision rates under sunset and night; CLAHE does not.

Supplemental Video

Pipeline overview and asynchronous active-perception animation from the paper supplemental materials.

Full pipeline overview — generative neural sensor in the loop.

Asynchronous active perception — high-latency recovery decoupled from control.

Qualitative Comparisons

ExDark real-world low-light detection: original input, MambaSFLNet (IROS 2025 SOTA), and our generative neural sensor.

Original low-light
Original
MambaSFLNet
MambaSFLNet
Ours
Ours

Closed-Loop CARLA (Thunderhill)

Identical obstacle seeds across Day / Sunset / Night. YOLO is daylight-trained; the generative sensor maps degraded frames back into the detector’s operating domain.

Raw camera
Raw camera
Relit
Neural sensor output
Thunderhill track in CARLA

Virtual Thunderhill Raceway — closed-loop evaluation environment.

Results

Selected tables from the paper. Best in red, second-best in blue.

ExDark mean AP (subset)

Method Bicycle Car Dog People Mean
RetinexNet0.7900.8200.7210.7840.736
MambaSFLNet 0.821 0.824 0.779 0.809 0.766
Ours 0.886 0.878 0.933 0.851 0.871

Full 12-category table in the paper — Ours leads every category.

vKITTI2 domain gap (Fog)

Method F1 mAP@50
Baseline0.6810.544
CLAHE0.7810.635
MambaSFLNet0.5790.452
Ours0.8550.807

Pixel-reconstruction SOTA degrades below the unenhanced baseline under fog.

Navigation safety (5 laps, MPC_DLC)

Method Collisions Rate (%) Latency
Daytime (Oracle)20.4 ± 2.422.47 ± 3.071.7 ms
Dark (No Fix)29.6 ± 3.632.61 ± 4.501.7 ms
Dark + CLAHE31.4 ± 4.134.39 ± 3.642.0 ms
Dark + Gen. (Ours)22.0 ± 7.224.55 ± 6.3062.0 ms

Generative sensing restores near-daylight collision margins under night.

Event-driven triggering (Sunset)

Mode Collisions Frames Relit Latency GPU Util
Continuous Relight30.4 ± 2.2100%62.0 ms95.0%
Event-Driven (τ=0.3) 23.4 ± 2.1 0.4% 2.0 ms 0.4%

Sparse activation is both cheaper and safer when lighting is only partially degraded.

Detection confidence histogram with activation thresholds

Confidence histogram over a low-light lap; dashed lines mark τlow=0.3 and τhigh=0.5.

Code & Simulator

Closed-loop CARLA Thunderhill stack, relighting service, MPC_DLC controller, and paired A/B evaluation scripts:

jayhsu0627/Wolverine_CARLA_Thunderhill

BibTeX

@inproceedings{xu2026neuralsensor,
  title     = {Real-Time Diffusion Relighting as a Neural Sensor:
               Closing the Low-Light Domain Gap for Robotic Perception},
  author    = {Xu, Shengjie and Gao, Alexander and Rai, Anshul and
               Lee, Dae Yeol and Su, Guan-Ming and Lin, Ming C.},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots
               and Systems (IROS)},
  year      = {2026}
}