1,255 research outputs found
Pix2HDR -- A pixel-wise acquisition and deep learning-based synthesis approach for high-speed HDR videos
Accurately capturing dynamic scenes with wide-ranging motion and light
intensity is crucial for many vision applications. However, acquiring
high-speed high dynamic range (HDR) video is challenging because the camera's
frame rate restricts its dynamic range. Existing methods sacrifice speed to
acquire multi-exposure frames. Yet, misaligned motion in these frames can still
pose complications for HDR fusion algorithms, resulting in artifacts. Instead
of frame-based exposures, we sample the videos using individual pixels at
varying exposures and phase offsets. Implemented on a pixel-wise programmable
image sensor, our sampling pattern simultaneously captures fast motion at a
high dynamic range. We then transform pixel-wise outputs into an HDR video
using end-to-end learned weights from deep neural networks, achieving high
spatiotemporal resolution with minimized motion blurring. We demonstrate
aliasing-free HDR video acquisition at 1000 FPS, resolving fast motion under
low-light conditions and against bright backgrounds - both challenging
conditions for conventional cameras. By combining the versatility of pixel-wise
sampling patterns with the strength of deep neural networks at decoding complex
scenes, our method greatly enhances the vision system's adaptability and
performance in dynamic conditions.Comment: 14 pages, 14 figure
Convolutional sparse coding for high dynamic range imaging
Current HDR acquisition techniques are based on either (i) fusing multibracketed, low dynamic range (LDR) images, (ii) modifying existing hardware and capturing different exposures simultaneously with multiple sensors, or (iii) reconstructing a single image with spatially-varying pixel exposures. In this paper, we propose a novel algorithm to recover high-quality HDRI images from a single, coded exposure. The proposed reconstruction method builds on recently-introduced ideas of convolutional sparse coding (CSC); this paper demonstrates how to make CSC practical for HDR imaging. We demonstrate that the proposed algorithm achieves higher-quality reconstructions than alternative methods, we evaluate optical coding schemes, analyze algorithmic parameters, and build a prototype coded HDR camera that demonstrates the utility of convolutional sparse HDRI coding with a custom hardware platform
Video from a Single Coded Exposure Photograph using a Learned Over-Complete Dictionary
Cameras face a fundamental tradeoff between the spatial and temporal resolution - digital still cameras can capture images with high spatial resolution, but most high-speed video cameras suffer from low spatial resolution. It is hard to overcome this tradeoff without incurring a significant increase in hardware costs. In this paper, we propose techniques for sampling, representing and reconstructing the space-time volume in order to overcome this tradeoff. Our approach has two important distinctions compared to previous works: (1) we achieve sparse representation of videos by learning an over-complete dictionary on video patches, and (2) we adhere to practical constraints on sampling scheme which is imposed by architectures of present image sensor devices. Consequently, our sampling scheme can be implemented on image sensors by making a straightforward modification to the control unit. To demonstrate the power of our approach, we have implemented a prototype imaging system with per-pixel coded exposure control using a liquid crystal on silicon (LCoS) device. Using both simulations and experiments on a wide range of scenes, we show that our method can effectively reconstruct a video from a single image maintaining high spatial resolution
Efficient Space-Time Sampling with Pixel-wise Coded Exposure for High Speed Imaging
Cameras face a fundamental tradeoff between spatial and temporal resolution. Digital still cameras can capture images with high spatial resolution, but most high-speed video cameras have relatively low spatial resolution. It is hard to overcome this tradeoff without incurring a significant increase in hardware costs. In this paper, we propose techniques for sampling, representing and reconstructing the space-time volume in order to overcome this tradeoff. Our approach has two important distinctions compared to previous works: (1) we achieve sparse representation of videos by learning an over-complete dictionary on video patches, and (2) we adhere to practical hardware constraints on sampling schemes imposed by architectures of current image sensors, which means that our sampling function can be implemented on CMOS image sensors with modified control units in the future. We evaluate components of our approach - sampling function and sparse representation by comparing them to several existing approaches. We also implement a prototype imaging system with pixel-wise coded exposure control using a Liquid Crystal on Silicon (LCoS) device. System characteristics such as field of view, Modulation Transfer Function (MTF) are evaluated for our imaging system. Both simulations and experiments on a wide range of scenes show that our method can effectively reconstruct a video from a single coded image while maintaining high spatial resolution
{HDR} Denoising and Deblurring by Learning Spatio-temporal Distortion Model
We seek to reconstruct sharp and noise-free high-dynamic range (HDR) video from a dual-exposure sensor that records different low-dynamic range (LDR) information in different pixel columns: Odd columns provide low-exposure, sharp, but noisy information; even columns complement this with less noisy, high-exposure, but motion-blurred data. Previous LDR work learns to deblur and denoise (DISTORTED->CLEAN) supervised by pairs of CLEAN and DISTORTED images. Regrettably, capturing DISTORTED sensor readings is time-consuming; as well, there is a lack of CLEAN HDR videos. We suggest a method to overcome those two limitations. First, we learn a different function instead: CLEAN->DISTORTED, which generates samples containing correlated pixel noise, and row and column noise, as well as motion blur from a low number of CLEAN sensor readings. Second, as there is not enough CLEAN HDR video available, we devise a method to learn from LDR video in-stead. Our approach compares favorably to several strong baselines, and can boost existing methods when they are re-trained on our data. Combined with spatial and temporal super-resolution, it enables applications such as re-lighting with low noise or blur
SoDaCam: Software-defined Cameras via Single-Photon Imaging
Reinterpretable cameras are defined by their post-processing capabilities
that exceed traditional imaging. We present "SoDaCam" that provides
reinterpretable cameras at the granularity of photons, from photon-cubes
acquired by single-photon devices. Photon-cubes represent the spatio-temporal
detections of photons as a sequence of binary frames, at frame-rates as high as
100 kHz. We show that simple transformations of the photon-cube, or photon-cube
projections, provide the functionality of numerous imaging systems including:
exposure bracketing, flutter shutter cameras, video compressive systems, event
cameras, and even cameras that move during exposure. Our photon-cube
projections offer the flexibility of being software-defined constructs that are
only limited by what is computable, and shot-noise. We exploit this flexibility
to provide new capabilities for the emulated cameras. As an added benefit, our
projections provide camera-dependent compression of photon-cubes, which we
demonstrate using an implementation of our projections on a novel compute
architecture that is designed for single-photon imaging.Comment: Accepted at ICCV 2023 (oral). Project webpage can be found at
https://wisionlab.com/project/sodacam
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