Event-based Vision: A Survey

Event cameras are bio-inspired sensors that differ from conventional frame cameras: Instead of capturing images at a fixed rate, they asynchronously measure per-pixel brightness changes, and output a stream of events that encode the time, location and sign of the brightness changes. Event cameras offer attractive properties compared to traditional cameras: high temporal resolution (in the order of microseconds), very high dynamic range (140 dB vs. 60 dB), low power consumption, and high pixel bandwidth (on the order of kHz) resulting in reduced motion blur. Hence, event cameras have a large potential for robotics and computer vision in challenging scenarios for traditional cameras, such as low-latency, high speed, and high dynamic range. However, novel methods are required to process the unconventional output of these sensors in order to unlock their potential. This paper provides a comprehensive overview of the emerging field of event-based vision, with a focus on the applications and the algorithms developed to unlock the outstanding properties of event cameras. We present event cameras from their working principle, the actual sensors that are available and the tasks that they have been used for, from low-level vision (feature detection and tracking, optic flow, etc.) to high-level vision (reconstruction, segmentation, recognition). We also discuss the techniques developed to process events, including learning-based techniques, as well as specialized processors for these novel sensors, such as spiking neural networks. Additionally, we highlight the challenges that remain to be tackled and the opportunities that lie ahead in the search for a more efficient, bio-inspired way for machines to perceive and interact with the world

Application of Novel Lossless Compression of Medical Images Using Prediction and Contextual Error Modeling

Conduction of tele-3D-computer assisted operations as well as other telemedicine procedures often requires highest possible quality of transmitted medical images and video. Unfortunately, those data types are always associated with high telecommunication and storage costs that sometimes prevent more frequent usage of such procedures. We present a novel algorithm for lossless compression of medical images that is extremely helpful in reducing the telecommunication and storage costs. The algorithm models the image properties around the current, unknown pixel and adjusts itself to the local image region. The main contribution of this work is the enhancement of the well known approach of predictor blends through highly adaptive determination of blending context on a pixel-by-pixel basis using classification technique. We show that this approach is well suited for medical image data compression. Results obtained with the proposed compression method on medical images are very encouraging, beating several well known lossless compression methods. The predictor proposed can also be used in other image processing applications such as segmentation and extraction of image regions

Kompresija slika bez gubitaka uz iskorištavanje tokovnog modela za izvođenje na višejezgrenim računalima

Image and video coding play a critical role in present multimedia systems ranging from entertainment to specialized applications such as telemedicine. Usually, they are hand–customized for every intended architecture in order to meet performance requirements. This approach is neither portable nor scalable. With the advent of multicores new challenges emerged for programmers related to both efficient utilization of additional resources and scalable performance. For image and video processing applications, streaming model of computation showed to be effective in tackling these challenges. In this paper, we report the efforts to improve the execution performance of the CBPC, our compute intensive lossless image compression algorithm described in [1]. The algorithm is based on highly adaptive and predictive modeling, outperforming many other methods in compression efficiency, although with increased complexity. We employ a high–level performance optimization approach which exploits streaming model for scalability and portability. We obtain this by detecting computationally demanding parts of the algorithm and implementing them in StreamIt, an architecture–independent stream language which goal is to improve programming productivity and parallelization efficiency by exposing the parallelism and communication pattern. We developed an interface that enables the integration and hosting of streaming kernels into the host application developed in general–purpose language.Postupci obrade slikovnih podataka su iznimno zastupljeni u postojećim multimedijskim sustavima, počev od zabavnih sustava pa do specijaliziranih aplikacija u telemedicini. Vrlo često, zbog svojih računskih zahtjeva, ovi programski odsječci su iznimno optimirani i to na niskoj razini, što predstavlja poteškoće u prenosivosti i skalabilnosti konačnog rješenja. Nadolaskom višejezgrenih računala pojavljuju se novi izazovi kao što su učinkovito iskorištavanje računskih jezgri i postizanje skalabilnosti rješenja obzirom na povećanje broja jezgri. U ovom radu prikazan je novi pristup poboljšanja izvedbenih performansi metode za kompresiju slika bez gubitaka CBPC koja se odlikuje adaptivnim modelom predviđanja koji omogućuje postizanje boljih stupnjeva kompresije uz povećanje računske složenosti [1]. Pristup koji je primjenjen sastoji se u implementaciji računski zahtjevnog predikcijskog modela u tokovnom programskom jeziku koji omogućuje paralelizaciju izvornog programa. Ovako projektiran predikcijski model može se iskoristiti kroz sučelje koje smo razvili a koje omogućuje pozivanje tokovnih računskih modula i njihovo paralelno izvođenje uz iskorištavanje više jezgri

Spatial and temporal aspects of land use in the urban-rural fringe in china: a GIS approach

Since the reform in 1979, China's rural and urban economies have been extremely active. This has accelerated greatly the urbanisation process in the peripheral areas of metropolises. Urban regions extended into rural areas by way of urban sprawl and population concentration in the rural-urban fringe, in which the types and structures of land use changed rapidly. The rural-urban fringe has been an extremely active area in contemporary Chinese socio-economy. It is also a belt of concentration of development and construction of rural and urban kinds. In seeking to apply geographical information systems to such an important area of land use change, this research studies the general principles of the formation, evolution and development of rural-urban fringe with a case study in Tianhe District of Guangzhou Municipality, China. This research analyses the following three aspects of land use change. Firstly, the land use conditions and situations are discussed in the form of their fundamental characteristics in various years. Secondly, the spatial changes of land uses are characterised in terms of the distance from the city centre including the effects of the physical landscape. Finally, the main emphasis is put upon the impacts of policies on land use distribution. Three different time periods (1973, 1993 and predicted 2010) are applied to compare the changes of land use. According to the analysis of the trend of land use change in this study, the development of Tianhe District from a traditional rural area to a rural-urban fringe is a considered as result of the Guangzhou urban sprawl. Its specific location, economic development levels, population conditions and policy advantages have influenced this evolution process and brought about the spatial changes and spatial structure of land use. Keywords: Land use change, rural-urban fringe, China, GI

Zerotree-based stereoscopic video CODEC

Due to the provision of a more natural representation of a scene in the form of left and right eye views, a stereoscopic imaging system provides a more effective method for image/video display. Unfortunately the vast amount of information that must be transmitted/stored to represent a stereo image pair/video sequence, has so far hindered its use in commercial applications. However, by properly exploiting the spatial, temporal and binocular redundancy, a stereo image pair or a sequence could be compressed and transmitted through a single monocular channel’s bandwidth without unduly sacrificing the perceived stereoscopic image quality. We propose a timely and novel framework to transmit stereoscopic data efficiently. We propose a timely and novel framework to transmit stereoscopic data efficiently. We present a new technique for coding stereo video sequences based on discrete wavelet transform DWT technology. The proposed technique particularly exploits zerotree entropy ZTE coding that makes use of the wavelet block concept to achieve low bit rate stereo video coding. One of the two image streams, namely, the main stream, is independently coded by a zerotree video CODEC, while the second stream, namely, the auxiliary stream, is predicted based on disparity compensation. A zerotree video CODEC subsequently codes the residual stream. We compare the performance of the proposed CODEC with a discrete cosine transform DCT -based, modified MPEG-2 stereo video CODEC. We show that the proposed CODEC outperforms the benchmark CODEC in coding both main and auxiliary streams

Patient-centred care: Patients’ experiences of and responses to the National Health Service (NHS) Health Check programme in general practice

This thesis investigates patients’ experiences of and responses to NHS Health Checks, towards the goal of improving patient-centred care. The findings are based on analyses of semi-structured interviews with sixteen Darlington-based patients who had recently undergone an NHS Health Check. I analysed patients’ satisfaction with the NHS Health Check and their expectations about the models and types of care their GP surgery should provide. This analysis identified five aspects of the design and delivery of NHS Health Checks which did not meet patients’ expectations: 1. The NHS Health Check did not meet patients’ expectations for a general health check which would provide empathy and support for all of their health priorities and concerns. 2. Patients felt that eligibility to attend an NHS Health Check should be based on patients’ opinions about when they need or want to have a health check and that access to NHS Health Checks should not be restricted, through age-based criteria. 3. During the NHS Health Check, health was measured in ways that caused some patients discomfort, stress, or anxiety. 4. Patients did not think that all the measures of health used to define their bodies were relevant to their lives. Patients did not necessarily agree with, support, or believe in these definitions of their health. 5. Reliance on general advice about self-help, specifically with the letter of results, did not effectively support all patients to improve their future health outcomes. Some patients found the general advice did not apply to their individual circumstances. The current format of an NHS Health Check does not adapt well to patients’ needs and preferences as individuals and the particular health measures and health outcomes which they think are most important. Improved patient-centred provision of NHS Health Checks may help to improve patient satisfaction