5 research outputs found
A micropower centroiding vision processor
Published versio
Image Sensors in Security and Medical Applications
This paper briefly reviews CMOS image sensor technology and its utilization in security and medical
applications. The role and future trends of image sensors in each of the applications are discussed. To provide
the reader deeper understanding of the technology aspects the paper concentrates on the selected applications
such as surveillance, biometrics, capsule endoscopy and artificial retina. The reasons for concentrating on these
applications are due to their importance in our daily life and because they present leading-edge applications for
imaging systems research and development. In addition, review of image sensors implementation in these
applications allows the reader to investigate image sensor technology from the technical and from other views
as well
Bio-inspired electronics for micropower vision processing
Vision processing is a topic traditionally associated with neurobiology; known to encode,
process and interpret visual data most effectively. For example, the human retina;
an exquisite sheet of neurobiological wetware, is amongst the most powerful and efficient
vision processors known to mankind. With improving integrated technologies, this has
generated considerable research interest in the microelectronics community in a quest to
develop effective, efficient and robust vision processing hardware with real-time capability.
This thesis describes the design of a novel biologically-inspired hybrid analogue/digital
vision chip ORASIS1 for centroiding, sizing and counting of enclosed objects. This chip is
the first two-dimensional silicon retina capable of centroiding and sizing multiple objects2
in true parallel fashion. Based on a novel distributed architecture, this system achieves
ultra-fast and ultra-low power operation in comparison to conventional techniques.
Although specifically applied to centroid detection, the generalised architecture in fact
presents a new biologically-inspired processing paradigm entitled: distributed asynchronous
mixed-signal logic processing. This is applicable to vision and sensory processing applications
in general that require processing of large numbers of parallel inputs, normally
presenting a computational bottleneck.
Apart from the distributed architecture, the specific centroiding algorithm and vision
chip other original contributions include: an ultra-low power tunable edge-detection circuit,
an adjustable threshold local/global smoothing network and an ON/OFF-adaptive spiking
photoreceptor circuit.
Finally, a concise yet comprehensive overview of photodiode design methodology is provided
for standard CMOS technologies. This aims to form a basic reference from an engineering
perspective, bridging together theory with measured results. Furthermore, an
approximate photodiode expression is presented, aiming to provide vision chip designers
with a basic tool for pre-fabrication calculations