1,720,969 research outputs found
A Digital Imager Architecture with On-Chip Compression for High-Speed Imaging Applications
No full textIn response to the demand for high-resolution, high dynamic range, and high frame rate image sensors with low power consumption, the early 2000s saw a surge in research on on-chip compression techniques. These aimed to reduce data transmission bandwidth with minimal image quality degradation, balancing compression performance with CMOS planar technology limitations. Now, thanks to 3D integration and recent advancements in SPAD arrays and digital pixel sensors, these techniques are becoming interesting again. This work presents a novel sensor architecture suitable for digital imagers featuring on-chip compression. The proposed solution employing an in-pixel shot noise-based differential modulation scheme (DPCM) combined with an intra-pixel suppression scheme to exploits both temporal and spatial redundancies. Preliminary evaluations of compression performance through numerical simulations using synthesized videos of real scenes have demonstrated the advantages of the proposed solution achieving simultaneous high-fidelity image reconstruction (PSNR ∼28 dB) and a high compression ratio at the same time (CR\~{}27). This reveals significant potential for further enhancements, paving the way for high speed and dynamic range imaging in various applications
Comparison of background-rejection techniques for SPAD-based LiDAR systems
No full textWe present the results of Montecarlo simulations and measurements focusing on the analysis of two techniques aimed at reducing the negative effect of background light in Single Photon Avalanche Diode (SPAD)-based Light Detection And Ranging (LiDAR) systems. The first technique, known as photon coincidence technique, exploits the temporal proximity of multiple detections to reject background light and maximize the detection of photons belonging to the target reflection. The second technique, named Auto-Sensitivity (AS) technique, reduces the photon-detection probability (PDP) if a certain background illumination level is detected, to avoid the risk of saturating SPADs due to intense background level. The two methods are first compared to each other, showing that the photon coincidence technique outperforms the AS technique. Then, the two techniques are operated together, resulting in an increase of the maximum achievable measurement range if the AS technique is applied on top of the photon coincidence technique
Comparative evaluation of background-rejection techniques for SPAD-based LiDAR systems
No full textThis paper presents the analysis and comparative evaluation of three background-rejection techniques implemented in CMOS processes for Single Photon Avalanche Diode (SPAD)-based Light Detection and Ranging (LiDAR) systems, using both Monte Carlo simulations and laboratory measurements. The first technique, known as photon coincidence technique, uses the temporal proximity of multiple detections to reject background light and maximize the detection of photons belonging to the reflected laser pulse. With the second technique, named Auto-Sensitivity (AS) technique, background light is rejected by automatically reducing the SPAD photon-detection probability (PDP), in order to avoid sensor saturation due to the intense environment illumination. The third technique we consider is the last-hit detection, which is able to detect and timestamp the last event impinging on the sensor over the acquisition window rather than the first, maximizing the system performance for long distance targets. The photon coincidence technique and AS technique are first compared to each other, showing the photon coincidence technique to outperform the AS technique. Then, the two techniques are applied together, resulting in an increase of the measurement range. Furthermore, a detailed analysis considering three different implementations of the photon coincidence technique is presented, showing pros and cons of each implementation and how the performance is affected. The last set of results focuses on the last-hit detection, which is compared against the standard detection paradigm (first-hit), showing not only an improvement for long distance targets (as expected), but an overall increase in system performance in terms of both success rate and SNR
A -Pixel Flash LiDAR SPAD Imager with Distributed Pixel-to-Pixel Correlation for Background Rejection, Tunable Automatic Pixel Sensitivity and First-Last Event Detection Strategies for Space Applications
No full textLight detection and ranging (LiDAR) systems are enabling new applications in the field of spacecraft navigation, planetary exploration, as well as docking and landing operations. Wide time-of-flight (ToF) range, high speed and spatial resolution, tolerance to background (BG) noise, high dynamic range and radiation hardness represent some of key features to operate in this harsh environment. Among all technologies, direct ToF sensors based on CMOS single-photon avalanche diodes (SPAD) and time-to-digital converter (TDC) pixel arrays have gradually earned their place in 3D imaging due to their performance and system integrability [1]–[4]
A 500 × 500 Pixel Image Sensor with Arbitrary Number of RoIs per Frame and Image Filtering for Center of Mass Estimation
No full textThis paper reports on a 500 x 500 pixel CMOS image sensor allowing multiple Regions of Interest (RoI) per frame with programmable number and size, aimed at minimizing the amount of data to be delivered off-chip and at reducing its power consumption. The proposed sensor architecture offers large flexibility to face different use case scenarios and it is suitable to any pixel array. The sensor embeds image background subtraction capability and integrates a computing layer which pre-filters the pixels to estimate the Center of Mass (CoM) of the RoIs up to a maximum size of 128 x 128 pixels. The 8 μm pixel sensor is manufactured in a 110 nm 1P4M CMOS technology and occupies 25 mm2. The chip, operating in standard imaging mode, consumes 4.9 mW at 30 fps
A 500 x 500 Pixel Image Sensor with Multiple Regions of Interest for Center of Mass-Based Event Detection
No full textThis article reports on a 500×500 pixel CMOS vision sensor allowing multiple regions of interest (RoIs) per frame with programmable and arbitrary number, size, and shape, aimed at minimizing the delivered data and at reducing the required amount of off-chip computation. In the proposed application, the center of mass (CoM) terms of the RoIs, computed by the sensor, are used to monitor the activity in some zones of the scene to switch the sensor to a pixel delivering mode, enabling high-level image processing upon request through an external processing platform. Anomalies are detected as changes in the x–y position of the CoM. The embedded CoM processor (CoMP) extracts the centroid terms of the selected subwindows, managing a maximum RoI size of 128×128 pixels. The parameters of each RoI are uploaded rowwise through a serial interface (SI). The sensor with 8- μ m pixel pitch is manufactured in a 110-nm 1P4M CMOS technology and occupies 25 mm2. The chip, operating in standard imaging mode (IM), consumes 4.9 mW at 20 fps
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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