Tuesday, December 31, 2013

CMOS Sensor Operation in Camera

Until recently the industrial digital vision sensor market was dominated by the CCD array. However technological advances in CMOS production techniques have led to a gradual increase in the popularity of this sensor type. Like CCD arrays, CMOS sensors are also formed on a silicon substrate but the structure is more akin to that of other CMOS technology such as RAM and ROM memory devices.

The diagram below is that of an actual CMOS sensor showing the active pixel area in green and the area occupied by the on chip circuitry in yellow, which replaces that of the shuttered area on a CCD based sensor. The on chip circuitry actually converts the charge into voltage on each pixel whereas the CCD sensor shifts the charge vertically row by row, and then horizontally pixel by pixel to be converted to voltage when it reaches one or more output nodes. This gives CMOS sensors an advantage when it comes to windowing or a region of interest as the pixels can be read out randomly. CCD sensors can only limit its region of interest vertically with the resulting image always containing the data for the full image width.
The on chip active amplifier and the sampling capacitor give CMOS sensors advantages in terms of speed, full well capacities and much improved response characteristics yet introduce dark current level noise and higher black pixel content. CMOS sensors can also produce higher levels of fixed pattern noise than that of CCD, but this type of noise can be easily removed with a software filter.

The development of CMOS sensor technology has been a rapid and varied process. The initial aim of CMOS sensors was to match the imaging performance of CCD technology, with lower power requirements and at less cost. To achieve this performance it was discovered that a much greater level of manufacturing process adaptation and deeper submicron lithography were required than initially expected. This led to the desired CMOS performance but increased development costs more than anticipated.

At first the low power feature of the CMOS imaging sensors was set to be one of their distinct advantages, however the improved development of CCD sensors means that while CMOS has the advantage in this area, the margin is now much smaller.

The integration of on chip control circuitry with the CMOS imager provides the sensor with greater flexibility and integration, the downside has been the introduction of greater noise levels. Both CMOS and CCD imaging sensors still require support chips to process the image, however CMOS imagers can be produced with more functionality on the sensor chip, as shown below.
The spectral response of a CMOS sensor differs from that of the CCD sensors in that the peak response is sited at around 700Nm. Both sensors operate over the same range, typically 200Nm to 1100Nm.

The main advantages of CMOS imaging sensors still remain as faster response, increased integration flexibility and lower on-chip power demands. However the image quality has yet to match that of the CCD and the supporting chips required to increase the CMOS image quality goes some way to squander its previous advantages. Yet neither sensor is categorically superior to the other. They both have their own advantages and disadvantages and with CMOS developers working on the image quality, and CCD developers aiming to reduce power demands and increase flexibility, the existing margins in place to decide which sensor is most suitable for an application look to narrow further.

Friday, December 20, 2013

Electronic Guardian Angel That Spots The Bad Guys And Respects Your Privacy


Electronic Guardian Angel That Spots The Bad Guys And Respects Your Privacy

New computerized surveillance cameras detect & confirm threats from one meter to one mile

A former BT communications manager, turned inventor, reckons that his intelligent CCTV surveillance company has developed a “Guardian Angel” video surveillance technology, which can keep us all safe from crime and violence whilst protecting our Right to Privacy. Stuart Thompson was a recognized innovator with British Telecom, where he led in the development of the high speed modems that introduced broadband internet. He has now used his high-speed expertise and ingenuity to develop an award-winning intelligent moving camera system that will passively observe and ignore innocent goings-on, but quickly alert human operators to suspicious or dangerous activity. In addition to crime-busting on Britain's streets, Stuart Thompson claims the system can significantly enhance Homeland Security whilst unobtrusively safeguarding our schools or our elderly and vulnerable citizens in care homes and hospitals.

Thompson is President and owner of Viseum UK. He reminds us how the Director General of MI5 recently warned that thousands of Islamic extremists living in the UK, currently saw their British home as a legitimate target. He adds that the UK Home Office also admitted the E-Borders programme had failed to detect and intercept major crime suspects at our national borders. Elsewhere at another end of the spectrum, the CQC recently recommended surveillance camera installation in care homes to protect vulnerable adults from abuse by a few reckless and abusive members of staff. In a busy, populated area, these all represent significant albeit very different security challenges that have dogged ordinary CCTV providers and the security industry for decade. As Stuart Thompson puts it;

“Discerning suspicious and potentially harmful indicators within a sea of mundane, innocent routine is a needle-in-the-haystack task, that human beings are exceptionally bad at.”

However the London inventor, claims he has the solution in a computer-automated CCTV system, optimised for the complex and busy environments that we live and work in. Viseum UK’s globally patented Intelligent Moving Camera (IMC) is controlled by iVOS (an Intelligent Virtual Operator system). Viseum intelligent CCTV systems can recognize and track suspicious activity and a known hooligan, criminal or terrorist, with far greater reliability than any human CCTV operator. The system uses a ring of automated surveillance cameras to passively gaze in every direction and be aware of all activity around them. The system quickly learns its surroundings and “normal” activity. However, Thompson points out that footage of routine events largely stays within the camera unit – unseen by a human. Only when the iVOS Virtual Operator detects unusual or potentially suspicious and dangerous activity, will a human operator in a central control room, be alerted. The security operator will be shown edited footage of what the Viseum system spotted. He can then alert the authorities, emergency services or security patrols and guide them onto the scene. In the meantime, the Intelligent Moving Camera system has automatically fired into evidence collection mode. It takes control of a high clarity pan, tilt zoon camera to capture forensic quality images of what is going on and who is involved. Thompson explains that his Find, Fix, Follow (F3) capability uses behaviour algorithms, plus face, person and vehicle number plate recognition technology to track a suspect or perpetrator wherever they go within the streets, buildings and corridors covered by the Viseum camera network. Viseum iVOS is just as adept at spotting a suspiciously abandoned holdall, agitated behaviour, a neglected patient, or a harassed lone female late at night. However, should there be nothing untoward going on, then the images stay within the system’s hard-drive to be recorded over at a specified point. “I designed the IMC and iVOS systems to be virtual guardian angels, benignly gazing upon our daily lives, but ready to intervene should we be threatened,” 

Depending on the camera hardware used, each of these Viseum camera units delivers surveillance security from close quarters in a bedroom, through an airport and up to an area the size of an Olympic Park. Viseum's technology is well known to several police forces and borough councils, for the positive impact they have had upon crime and anti-social behaviour in the UK's public spaces. Conviction statistics show that criminals and ASBO offenders have good reason to fear them. Optimised for busy streets and crowded cities, with 360-degree coverage up to extreme distances, the Intelligent Moving Camera never blinks, never gets tired, looks in the wrong direction or gets distracted.

Viseum emphasises that it aims to optimise and supplement the human response to security incidents, rather than replace them completely. Viseum’s military force-protection & security experts, term this as "force-multiplication" freeing up people to do what they do best - interact with other people. Thompson explains, "Our surveillance solutions are the best. We offer security practitioners a continuous 360 degree unblinking stare across any area of responsibility, without the need for hundreds of CCTV cameras and valuable monitoring staff. It will also provide instantaneous forensic analysis of a previously unknown perpetrator's movements before and after the event. We can present patrols, incident commanders and the judiciary with an unbroken golden thread of video evidence, about what happened and who was involved. Viseum adds, "Viseum iVOS can also contribute to and enhance wider security at hospitals and care homes where intruders may attempt access or confused patients might wander off”.

Viseum has recently visited the USA to take part in a technology showcase at “Government Security Expo” in Dallas Texas. It was striking though not surprising that we share so many security challenges with the States,” said Thompson. “Local police chiefs, military base commanders, university campus supervisors, care home providers and Homeland Security practitioners all shared a fear of the low probability but high impact event that could occur within their area of responsibility. To use military parlance, they want perfect “Situational Awareness and Ground Truth” before, during and after an incident. We think that Viseum can deliver this for them and are actively involved in talks to secure an American partner to introduce our technology in this region.

For more information on the Viseum intelligent surveillance systems please visit http://www.viseum.co.uk
For further information on this release and other Viseum news and products, please contact Media contact Ian Cumming Director Business Development & Communication
via: t: +44 (0)1322 405724
e: press.office@viseum.co.uk

Sunday, December 8, 2013

MS SQL SERVER VS ORACLE 10G COMPARE

COMPARE MS SQL SERVER VS ORACLE 10G

SQL Server:

Pros:

Its easy installation, self-tuning capabilities, graphical administration, integrated business intelligence and extensive collection of help wizards

The total cost of ownership (TCO) of SQL Server 2005 is lower than that of Oracle
Specialized index on a computed column
Indexed View


Cons:

Locking and concurrency: SQL Server has no multi-version consistency model, which means that "writers block readers and readers block writers" to ensure data integrity


Performance and tuning:

a. DBA has no "real" control over sorting and cache memory allocation. The memory allocation is decided only globally in the server properties memory folder, and that applies for ALL memory and not CACHING, SORTING, etc.
b. All pages (blocks) are always 8k and all extents are always 8 pages (64k). This means you have no way to specify larger extents to ensure contiguous space for large objects.
c. In SQL Server, no range partitioning of large tables and indexes. In Oracle, a large 100 GB table can be seamlessly partitioned at the database level into range partitions.


With SQL Server 2005, INSERT, UPDATE, and DELETE statements are executed serially (MERGE is not supported).



Oracle:


Pros :

you can use Oracle on multiple platforms. Whereas Microsoft created SQL Server to be used on the Microsoft platform only, Oracle is available on multiple platforms, including Windows, Unix and now Linux, which is the foundation of Oracle's Real Application Clusters (RAC) strategy.


Locking and concurrency: "readers don't block writers and writers don't block readers." This is possible without compromising data integrity because Oracle will dynamically re-create a read-consistent image for a reader of any requested data that has been changed but not yet committed. In other words, the reader will see the data as it was before the writer began changing it (until the writer commits).


function-based indexes

Oracle will execute INSERT, UPDATE, DELETE, and MERGE statements in parallel when accessing both partitioned and non-partitioned database objects


Cons:

"Implementation of something similar to MSSQL Identity by using Oracle sequence would require reflecting the sequence name in the application or creating a trigger for each table/sequence pair.

Cost is higher
Required skilled DBA.


CONCURRENCY MODEL

concurrency control. The main differences are summarized in the table below:
Oracle Database 10g SQL Server 2005
Multi-version read consistency Always enabled. Not by default.
Must be enabled.
Non-escalating row-level locking Yes Locks escalate


SQL Server 2005 introduces two new isolation levels3:

read committed with snapshots (statement-level read consistency)
snapshot isolation (transaction-level read consistency)
These isolation levels correspond to Oracle’s READ COMMITTED and SERIALIZABLE isolation levels, respectively.