Neural Sensors: Learning Pixel Exposures with Programmable Sensors | ICCP/T-PAMI 2020

Julien N.P. Martel, Lorenz K. Mueller, Stephen J. Carey, Piotr Dudek, Gordon Wetzstein

We propose the learning of the pixel exposures of a sensor, taking into account its hardware constraints, jointly with decoders to reconstruct HDR images and high-speed videos from coded images.

 

The pixel exposures and their reconstruction are jointly learnt in an end-to-end encoder–decoder framework. The learning is performed taking into account hardware constraints so that the learnt shutter functions can be compiled down and used in a real programmable sensor–processor. This page describes the following project presented at ICCP 2020 and
published in T-PAMI in July 2020.

Tech Talk - 12 min

ABSTRACT

Camera sensors rely on global or rolling shutter functions to expose an image. This fixed function approach severely limits the sensors’ ability to capture high-dynamic-range (HDR) scenes and resolve high-speed dynamics. Spatially varying pixel exposures have been introduced as a powerful computational photography approach to optically encode irradiance on a sensor and computationally recover additional information of a scene, but existing approaches rely on heuristic coding schemes and bulky spatial light modulators to optically implement these exposure functions. Here, we introduce neural sensors as a methodology to optimize per-pixel shutter functions jointly with a differentiable image processing method, such as a neural network, in an end-to-end fashion. Moreover, we demonstrate how to leverage emerging programmable and re-configurable sensor–processors to implement the optimized exposure functions directly on the sensor. Our system takes specific limitations of the sensor into account to optimize physically feasible optical codes and we demonstrate state-of-the-art performance for HDR and high-speed compressive imaging in simulation and with experimental results.

T-PAMI 2020 ARTICLE

Files

  • technical paper (pdf)
  • supplement materials (pdf)

BibTeX
@article{Martel:2020:NeuralSensors,
author = {J.N.P. Martel and L.K. M\”{u}ller and S.J. Carey and P. Dudek and G. Wetzstein},
title = {{Neural Sensors: Learning Pixel Exposures for HDR Imaging and Video Compressive Sensing with Programmable Sensors}},
journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence},
volume = 42,
issue = 7,
pages = {1642–1653}
year = {2020},
}

Citation
J.N.P. Martel, L.K. Mueller, S.J. Carey, P. Dudek, G. Wetzstein, “Neural Sensors: Learning Pixel Exposures for HDR Imaging and Video Compressive Sensing with Programmable Sensors”, IEEE Transactions on Pattern Analysis and Machine Intelligence 42(7), 1642-1653. 2020, July.

System overview


Illustration of our end-to-end neural sensor framework. The exposure program of a sensor (physical layer) is learned end-to-end with a decoder (digital layer) for applications like video compressive sensing. Here, we show a single coded exposure captured with our prototype camera and several frames of the high-speed video reconstructed from this image showing an exploding balloon.

Hardware SETUP

Real captures of the coded images using the optimized shutter functions are performed with SCAMP-5, a programmable sensor processor.

SCAMP-5 is a 256×256 pixel array in which each pixel is equipped with a small processor and a few registers.

Results: Real captures

In the following, we show a few example scenes for video compressive sensing: The image on the left is the first coded frame as captured by SCAMP-5 and the reconstructed high-speed video is shown on the right. For each coded frame, we reconstruct 16 images.

Coded Exposure Image Reconstructed Video
Water Droplet (video contains 64 total frames from 4 coded frames)
Rotating Fan (video contains 64 total frames from 4 coded frames)
Jumping Frog (video contains 64 total frames from 4 coded frames)
Oscilloscope (video contains 16 total frames from 1 coded frame)
Balloon (video contains 32 total frames from 2 coded frames)

Related Projects

You may also be interested in related projects, where we apply the idea of Deep Optics, i.e. end-to-end optimization of optics and image processing, to other applications, like image classification, extended depth-of-field imaging, superresolution imaging, or optical computing.

  • Wetzstein et al. 2020. AI with Optics & Photonics. Nature (review paper, link)
  • Martel et al. 2020. Neural Sensors. ICCP & TPAMI 2020 (link)
  • Dun et al. 2020. Learned Diffractive Achromat. Optica 2020 (link)
  • Metzler et al. 2020. Deep Optics for HDR Imaging. CVPR 2020 (link)
  • Chang et al. 2019. Deep Optics for Depth Estimation and Object Detection. ICCV 2019 (link)
  • Peng et al. 2019. Large Field-of-view Imaging with Learned DOEs. SIGGRAPH Asia 2019 (link)
  • Chang et al. 2018. Hybrid Optical-Electronic Convolutional Neural Networks with Optimized Diffractive Optics for Image Classification. Scientific Reports (link)
  • Sitzmann et al. 2018. End-to-end Optimization of Optics and Imaging Processing for Achromatic Extended Depth-of-field and Super-resolution Imaging. ACM SIGGRAPH 2018 (link)